Yeah you're thinking like a logical employee and not management. You might have local management (OS, OM, maybe even ATM) that are actually good people that want to do good with their employees and care about their happiness and wellbeing but that's not management at the regional or national level. As Move78 said, they see it as "you want to take 2 CPCs and make them both trainees, why would I want to lose 2 CPCs and get trainees instead? That doesn't help my numbers." They just want bodies to fill up their short staffed facilities. Any transfer at all (except NEST), is a negative for that goal of theirs. They'll just accept someone that resigns instead and just find a new hire to fill that hole whose more likely to just take whatever the FAA gives them.
It's pathetic that the FAA (and probably most of the government really) hasn't figured out that the better you treat your employees, the better off the agency would be. Happy people that like their job and that are treated with respect make great recruiters. But alas, they'll just recruit Fortnite players instead. Screw logic.