If your hypothetical Knight Errant is in a Panther, those pirate bug 'Mechs are very likely to try to get behind that Panther, and have the speed to do so. Your Knight doesn't have the speed to avoid that, or to get a high enough modifier to give them a bad shot when they get there. End result, the farmers are happy because the Pirates had more valuable stuff to take than their crops and farm machinery; the Pirates are happy because they got the remains of a Panther for parts, and the only person who's really less than satisfied with the deal is your dispossessed Knight Errant.
Compare that to a Phoenix Hawk. The Pirates probably don't have more than maybe one lightweight 'Mech in their force faster than the P-Hawk, and perhaps an even thinner-skinned hovertank. If they do, the P-Hawk is tough to hit, so they may do some trivial damage without punching the back armor, and get an arm-mounted LL and MG at point-blank in reply. Hovertanks and 20 ton bug 'Mechs really hate that for some reason. The P-Hawk can at least maintain range from everything else, or close at his own convenience.
The Pirates can't burden their 'Mechs with arm-loads of loot without compromising their fighting abilities, and can't spread out to search, so they're frustrated. They can't catch the Knight, except for one or two individual units that are no match for the P-Hawk's greater firepower and armor, and can't run fast enough to avoid being trailed. In essence, it's a standoff at worst, if not in outright favor of the Knight, until the Pirates decide that there's nothing further to be gained.
If the Pirates show up with a lance of Heavies, no other single 'Mech is going to deal with that anyway, and the P-Hawk can at least trail them and try to harass any that fall behind or are hindered by carried loot.
Also, how difficult or expensive is it to get MG ammo? The Panther's SRMs may be slightly more difficult to find at the local flea market or general store. If your Panther pilot needs an actuator, he's got to order one from Combine space. A P-Hawk replacement part is probably available from suppliers in every major House and some Periphery realms.