One of my favorite of feeble retorts is a common response to the accusation that we (Americans) are essentially free because/if we are allowed to leave the country any time we wish. The assertion itself is incredibly weak (from my perspective) and I wouldn't think it would take much to knock the legs out from under it, but apparently I'm wrong. I've seen both the well-intentioned and well-informed whiff at this one time and time again. Among my favorite typical responses, "Well the other governments are less free so I don't have a choice!" What?!? That's the best you have? Silly commentators, you're conceding the premise just by giving that kind of answer!
If someone started walking at you and flailing his/her arms, would it not be assault when they hit you simply because you could have stepped aside? If every time I tried to enter my house, and you attempted to corral me into a cage, would you claim you weren't usurping my freedom because I could simply go live somewhere else? Would taking my car from me by force not constitute a theft simply because I could have put it somewhere else?
These are meant to be rhetorical questions. If they are stupid enough to start biting bullets on any of it, just stand back and let them hang themselves. Any other retort you can give to their claim that starts with, "Well yes, but..
." is giving them too much ground. Drag them kicking and screaming back to first principles. My guess is that anyone dumb enough to even make that initial assertion isn't going to make it out of that bog without some serious issues. Socratic method. It works.