This is 100% not correct. Alter-ego is a big word (kind of like Scab Jr.), lets be real careful about throwing it around.

Go! is a brand name operated by Mesa Air Group (MAG) on the Mesa Airlines operating certificate. The pilots are mesa pilots, part of Alpa, and not an alter-ego of any sort. Mesa also operates Fredom Airlines and Air Midwest (both on seperate certificates, but the pilots are all on the mesa alpa list).

Fredom airlines USED to be an alter-ego, but the old freedom (Freedom A) was disassembled and exists only as a name on the operating certificate.

GoJet is another alto-ego, but is not related to mesa or Go! in any way at all (other than Hulas and JO being scumbags of the same caliber).