I have this vision in my head of this naked dude streaming water jumping out of the shower with the shower curtain all tangled around him so he can grab his blaster and take out the jokers who just kicked in his bathroom door!
You really believe that your bathroom door will slow down someone that serious about coming after you long enough for you to get out of the shower and grab your gun?
Very few houses in my experience have hardened bathroom doors.
Personally, I believe in a layered defense where anything that requires a gun will trigger sufficient warning for me to get out of the shower. If you think you can do anything about it when you're in the shower and the goblins are coming in the bathroom door, that's a fine fantasy and I hope you enjoy it!