So, I know that United can't have over a certain number of 70 seat jets and the limit has already been reached. There is a limit for 50 seat United partner jets but that its hundreds more than are in service now.

I was also told that the flying UAX regionals do can't be more than a % of flights mainline operate.

Now here is the tricky part. Yesterday a Capt tells me that the % cap of flying UAX does only applies to 70+ seat jets, not 50 seat jets. So hypothetically ZW, XJT and Commutair could operate with all of United mainline grounded. Surely that can't be the case?