Thats because your a "regional" that flies 100 seat aircraft (or used to) for dirt regionals. I agree that it's a sham that it's ok on a seperate certificate by the own company, but scopes gotta come into play somewhere.
Nope, sorry Mesa does not operate (or has ever) 100 seaters. Largest aircraft is the CRJ900. 7 years ago management tried to start a 737-200 operation for CRJ900+20% rate which Mesa ALPA refused. The only reason why the CRJ900s are on property is because freedom was started as a non-union operation. Mesa pilots used all their "negotiating capital" during contract negotiations to fold Freedom into Mesa, create a master seniority list and end the whipsaw and the beginning of a GoJets/TSA like situation. So all flying was recaptured by Mesa from the non-union Freedom however the consequence was a really crappy contract.
But don't let facts and history that you're ignorant of get in the way of your judgement.