From the previous thread:
What is he trying to sit on? If you look in the Sit package it'll state to look for a valid target and that must be a matching type. Secondly what is the radius of the package? Centre the package on the chair or whatever you're trying to get him to use and give it a very short radius (not less than 30 though) and he should use it if its a valid target. He might get up and stand everyone now and then but he should basically stay in the one spot.
n.b. isn't idle drunk a Standing animation? Not sure if they can sit and be drunk at the same time.
Conditions? Keywords? It should work if he's in range assuming theres nothing else making the quest not start (make all aliases optional while debugging)