Everyone I know who left the WO for an AA competitor has been in class at mainline within 6 months of their departure if they wanted to be. The Blacklist thing is a rumor crafted by WO management and passed along by fear mongering WO pilots. Don’t trust anyone who tells you this. Especially if they’re senior to you.

AA desperately needs mainline pilots but needs WO pilots more. They’ll lie to you to keep you at the WO but once you’re gone to a competitor (which is the key part… going to someone they compete with makes it worth their while to steal you) they’ll bring you back to mainline, even when you leave as an WO FO and go to a place like Frontier, JetBlue, Southwest, Spirit etc. Just keep updating your app once you leave.