Seating a high primer in a case that has a bullet and powder already loaded is NOT as safe as seating the primer in an empty case.
Rarely, a primer that is not seating properly WILL go off while being seated. Since this primer did not seat properly, there may be an issue with the primer or case, and there IS a slight possibility that trying to seat it will set it off.
With powder and a bullet in the case, the primer will probably ignite the powder if it does go off. If the case is not confined by a die, then it MIGHT just poof the bullet out of the case and do no real harm. BUT, I have set off loaded rounds outside of a firearm (intentionally as a kid) and had the equivalent of a cherry bomb, except that it does blow brass shrapnel around instead of sawdust. That is definitely a sight hazard, at least. I would expect that it could remove fingers or worse.
Confined in a die, a loaded round is definitely a bomb if it does go off. Think firing a round in a gun with a barrel obstruction.
So, considering the previous thread about setting off a cartridge by using a shellholder for a press instead of the proper holder for a kenetic puller, I suggest that you sacrifice the bullet by pulling it with pliers, dump the powder and THEN try to reseat the primer.