I'd guess that there are plenty of 2nd amendment supporters who would be happy to ban flag-burning...There are indeed, and I know more than a few of them. They post on the same gun forums I do. What you see among the "pro gun" crowd is a pretty clearly ideological divide between Libertarians and traditional Conservatives. The Libertarians take the 1A, 4A, 5A, etc. just as seriously as the 2A, whereas the more traditional Conservatives tend - in my experience - to be a bit more narrowly focused. It's unfortunate, but real.
That said, I take it as encouraging that I feel like I'm seeing more libertarian thought and less of the "yee-haw, let's kill that fag" kind of stuff on one of the NC centric gun forums I post on. And lots of people take a fairly moderate approach, offering up strong defenses of the 2A, without doing the full-on "captain redneck" thing.
On a semi-related note... it's kinda sad how prevalent stereotyping - and making broad assumptions based on those stereotypes - is. For example, many people seem to assume that most active 2A advocates are, indeed, "redneck" types: from the South, with CSA flag stickers on their trucks, a Bible in their hip pocket, and a mouthful of chewing tobacco. But, while those people exist, most of the pro gun folks I know are actually well educated, level-headed, reasonable and rational.