Which then raises the question of why the front line units didn't have enough mechs in the first place. These machines appeared from the beginning of the invasion, before any of the clans had suffered significant losses. If they were a post tukayyid thing, then sure, but they weren't. Either way, it creates the impression that somebody forgot to pack enough mechs.
The idea that they were refits produced in the homeworlds to bulk up second line numbers for the invasion, rather than being retrofitted from captured hardware during the invasion, makes more sense to my brain. And it seems to fit with the master unit list giving several of the machines to the home clans as well.
And
I consider the info to either be flat-out wrong or a fabrication, preferring an introduction date of 3052,
after the Clans have been having a far rougher time than they anticipated. After all, even if they won every battle up to Tukayyid (which they nearly did), they'd still be taking damage from the units they're fighting. It's perfectly logical that they had more OmniMechs shot up beyond repair than they anticipated they'd have by the time of Tukayyid, forcing them to strip second line units of OmniMechs.
After all, even if they used the Year of Peace to take stock of what they needed, they likely still didn't realize how fast they were burning through their supplies in comparison to their
anticipated needs. Remember, after the Year of Peace ended, the Inner Sphere commanders knew what they were facing now, and quite a few Clusters were probably dragged into long, bloody meatgrinders that burned through munitions, Elemental suits, and OmniMechs at an accelerated rate compared to before. Sure, they probably
won those battles, but they would have lost far more OmniMechs than before. With the next supply shipment not likely to arrive in time for the Battle of Tukayyid, they had to make do with what they had. So they stripped second line units of their OmniMechs. But those second line units still needed 'Mechs to pilot until the supply shipment arrived.
Thus, the "C" refits.