Welsh is contracted to celtic until summer 2027
https://www.bbc.com/sport/articles/cldg6w9dg50o
Like above, any club signing Welsh now would need to pay at least what celtic are paying him, or Celtic will need to give him some sort of payoff to make the difference. It's feasible that he'd take a modest pay cut for regular football, but I don't see why he'd do that right now, whether its with us, Aberdeen, or anyone else.
Clubs are increasingly moving the recruitment responsibilities away from the manager, which makes sense since most managers don't even last a season thesedays. I'm sure players would prefer some kind of managerial stability at the club they are joining, but I'm sure what they're getting paid matters more.