Huh? TMO was the first carrier in the U.S. to officially release the 10.2.X update to Z10 and Q10 users. Yes, VZW accidentally let their users update for a brief time, but that was an accident. Their official release was after TMO's. ATT's was much later. There are a bunch of thread about it.
Since Z30's and Passports aren't on TMO, users have to buy unlocked devices, which update direct from BlackBerry. The only thing that usually holds up an update with TMO is Wi-Fi Calling and that's not supported with the Z30 and Passport, so updating through BlackBerry is fine. ATT user using ATT-locked devices will have to wait.
Does TMO have a history of blocking users? ATT certainly does... search for "ATT facetime block" "ATT hangouts block"... and there weren't feuds going on. Why fear monger?