I think it's rather that he's all for gun grabbing… until he's put into a situation where he'd want a gun for himself.

My guess is it's a joke assuming "all left wing people are anti-gun until they feel threatened." I can safely say that's definitely not true, I'm a left leaning trans gal and I've always supported responsible gun ownership, and I have a left leaning coworker who is in fact a gun owner who's been around guns all her life.