Right back at you

One thing that drives me crazy is when people feel they need to share their political views on hot-button issues with you in inappropriate situations (especially if I don't agree with them). I'm just not very good with snappy retorts, so I inevitably feel like an idiot for not coming up with a good response.
Case in point: I stopped at a gas station in Wisconsin to pick up a newspaper. While waiting to pay, an older guy came in and also picked up a paper. The following conversation ensued (OG = older guy...actually, it also means "original gangster", but for our purposes it'll mean older guy):

OG: Looks like they'll be taking more money out of our pockets.

Me: Oh, really?

[OG frowns and opens up his newspaper and points to an article about a proposed universal health-care plan]

OG: $16 billion...gotta help them illegal aliens.

Me: Hmmmmmmm... [look away quickly]

I mean, is the local gas station mini-mart really the place to discuss either universal health care or immigration policy? And why can't I come up with a better response than to furrow my brow and try not to make further conversation? How do you reduce incredibly complex and difficult issues to idle 30-second chitchat? (In the end I figure he probably saw me drive off with my Illinois plates and figured I was just another big-city Chicago liberal...)