Lets examine that standing up. I belive the OWA cut a deal with the Kuritas and the Davions during the war robing the Star League of bases, men and resources. The Star LEague didn't push the OWA as hard because of the blood bath in TC and the fact they didn't want to get in a shooting match with Davion and Kurita forces who where messing with each other. The fact is the OWA miltary didn't inflict any major damage on the league, not surprising cause there miltary was weak to begin with.
Have you read Historical: Reunification War? If not, it might be a good idea, because your statement appears to be... erroneous. The Outworlds and their "mercenary" allies in the form of the Pitcairn Legion fought for five years against two Corps of Star League forces, continually frustrating them, and managing to do things like render one Corps largely combat-ineffective and get an entire Royal Brigade to surrender en masse. The Outworlds Alliance wasn't the subject of a grinding 20-year bloodfest like the Concordat, but the Outworlds Alliance fought a long and brutal war against heavily superior odds, in the face of outright atrocities and genocide conducted by Star League officers and their Combine auxiliaries, and managed to draw the war out far longer than the League planned, while inflicting far more damage than was ever expected. The Outworlds Alliance ultimately surrendered, but it was a negotiated surrender initiated by the Federated Suns and a new Star League senior officer in the theatre to avoid the several more years of highly-destructive warfare anticipated if the war continued as it was.
The Alliance government didn't cut any deals with the Combine - there was one instance of an Alliance planetary governor deliberately defecting his world to the Combine to avoid it being attacked, in defiance of local OAM forces who were dug in and ready to fight, and the Alliance military forces still fought a brief campaign over the world. That governor was assassinated shortly after. The Alliance Mechanized Divisions fought campaigns on a number of worlds against Combine forces, and on at least three worlds forced the Combine forces to retreat offworld.
As for the so-called vaunted Aerospace. Yes there one of the best in perpehery (And they say the IS..Though I never heard of them tangling with any major IS power since the Star League fall). Still there aerospace contingent does not make up for there poor ground forces. You still need boots on the ground to hold anything and the OWA boots are nothing to brag about.
AeroSpace forces make quite good defensive forces. Just ask the Diamond Sharks - when the other Clans were gunning for them during the Wars of Reaving, the Sharks made a point of never granting safcon, with their fighter forces bleeding the Steel Vipers across numerous worlds and forcing that Clan to ultimately have to pause and rebuild.
I'm not sure how the qualified "so-called vaunted AeroSpace" statement applies to the OA. The OA are a small Periphery realm that mustered five elite regiments of AeroSpace forces and were acknowledged as being skilled enough that other nations sent personnel to the OA to go through their training regime or as part of exchange programmes. Whatever the sources of your contempt for the OA forces are, the facts in canon are that the OA AeroSpace forces beat modern Snow Raven AeroSpace assets in a trial and are well-regarded by the Snow Ravens.
Are you quibbling with the Elite rating recorded in several sourcebooks against the Alliance Air Wings? Or are you perhaps arguing that Elite doesn't really mean Elite if it's Periphery forces?
The Outworlds Wastes are full of lost worlds that were attacked by Federated Suns and Combine forces looking to obtain tech and "destroy bandits" according to ISP3: Interstellar Expeditions. Despite that, the OA government kept a coherent realm together despite two vastly stronger neighbours. To intimate that the presence of five regiments of elite-rated AeroSpace forces had nothing to do with that would seem disingenious.
As for public resistence. The OWA people are perhaps the lease argressive people in BT. Heck they have show in the past that large groups of them would rather break up the OWA then try to support it. Not the kind of people that can be rosed to resist. They just happy to be left alone to live there lives and not be bother with politics
(Not really there fault if ya think about. Most BT people are Sheep-pole. There is not nationalism or patroic feeling in the bulk of them.)
Firstly, read Historical: Reunification War. No, seriously. The defense of the Outworlds Alliance during the War was in part explicitly because the population were riled up enough to actively resist, and they did so in the face of the Star League deliberately targeting civilian cities and populations and literally decimating local populations as an effort to stamp out resistance.
It also seems odd for you to suggest that the population of the OA can't be roused to resist, while at the same time saying that several planets decided to leave the OA rather than support a policy they didn't like. Several OA worlds disagreed with the Avellar policy of alliance with the Raven Alliance so much that they actively left the nation to stand on their own, rather than as a part of a greater nation, because of their principles. That doesn't sound like apathy.
I'm curious as to which sourcebooks dealing with the OA you've read and formed your opinions from, because I'm having some trouble reconciling what you're arguing with what I'm seeing in the various sourcebooks I've read dealing with them.