I'd qualify that statement- force is too strong of a word in this situation; I'd say try to arrange things so that the ISTJ is exposed, whether they think it or not. Like others said, a smaller gathering may be all that they need, eventually they being able to handle bigger events.
To answer your question: I know for myself, when I used to go to clubs and stuff I felt like everyone else was having fun and I was the only doof standing around. I guess that's the inferior Ne. Your question makes a good point that there are probably others with you at that club, who aren't the most outgoing, and they may seem chill, but they are probably there out of obligation with a group of friends, like me, an ISTJ. I think it's just a matter of getting over yourself in these situations, and have a drink! That will loosen you up.