This fantasy claim that the UA operation somehow puts more pressure on his pilots is what discredits him as a lying manipulative pig.
You can't argue that UAL's operation in ORD doesn't adversly affect pilot moral. Only on the most perfect of weather days does anything run on time, and in anything else flights get cancelled, people lose trips, get re-assigned all over the shop. Out of IAD there's all the fun of the New York airports. On a windless sunny afternoon Newark goes down the tubes, and it doesn't take much more for LGA to follow. Again, lost turns etc.
While that all happens in the other operations, it's not anything like at the same level as UAL.
Now you can argue, and probably will, that none of that is UALs fault and it's all Mesa's fault - but I'm not buying that. I regularly get pairings through ORD and think "no way is that going to go off without a hitch" and more often than not I'm right. UAL builds those schedules. It does it to all it's "regional partners", I once sat and watched every flight to a destination (all operated by SkyWest) from noon onwards slowly cancel (who knows what the passengers did, drive probably since the destination was pretty close in).
Ask any pilot who has flown in any other system - even US Air out of PHL, and let's face it, PHL is not exactly an airport that runs trouble free - and they were much happier even if they were flying for Mesa.
But I don't think any pilots are leaving Mesa BECAUSE of UAL, they're just leaving, and if UAL ran like a Swiss clock they'd be leaving anyway.
Sure - the whole letter has interesting motivations, including the possibility that it's a ploy to get planes for China. However it may just be a ploy to get UAL to get it's act together so Mesa can operate the contract at a profit. I mean in the end, for Mesa, a profitable UAL contract AND planes in China is better then one or the other.