Does Oliver Swanick give the finger to Nipton (instead of waving) before running to meet the player?

Yep.

It's an animation that a few characters will use in conversation.

A piece of animation that existed in Fo3, too, in fact. At least in the game files.

Did anyone shoot Swanick down as he was leaving? And doesn't he remind you of Fantastic in Helios One?

I always kill him, so I've never noticed.