No it would not as when you come out and people walk nearby, they also slide for a second.

Would animating a quickly opening automatic sliding door, that opens to revealing the AI character, who then walks off, work?

Indeed some slots seem to be very popular :)

Another odd thing I just spotted was AI's queuing to use one particular slot machine when loads of others were free. Initially the queue was 3 deep.

If I'm not wrong this also happens with normal players when you are standing near an entry/exit point outside the casino and another player comes out of the building.