He'll just crawl out of the crib. Usually, once they are out of the crib, there's no turning back.
You did the right thing holding the door. If there is a lock on the doorknob, I'd turn the doorknob around so that the lock is on the outside. Use it from the onset. When he is used to the door being locked for naps, you can use it at night and then he won't be coming out of his room before falling asleep. Simply undo the lock before you go to bed.
I would also pack the clothes up and put them in a box and put them in the closet for now. You can buy the kind of child-proof things that keep a closet door from opening, depending on what kind of closet door you have.
I wouldn't worry about him sleeping in the floor. As long as he is in his room, that is what matters. Eventually he will go back to the bed because it's more comfortable than the floor.
How long are his usual naps? Does he usually sleep for 2 hours? If that's a long nap, don't let him sleep so long. He needs a set time for naps during the day so that it doesn't mess up his sleep time at night.
He's not crabby because he slept in the floor. He may be crabby because he slept for so long, but not because he slept in the floor.
Make sure that he doesn't know that you are outside of the door holding it. The sooner you can turn the lock, the easier it will be for you.
Dawn