Yeah, that kind of follows along with the traditional lines that each genre seems to follow.  Country music has long been a place where, for lack of a better term, "conservative" principles have been welcome.  Lots of spiritual themes and hymns/gospel music inclusions on albums, lots of talk about what I would call responsible freedom, and definitely a lot of patriotism.

Rock music, and its ugly stepsister, pop music, have both been primarily about shallower sentiments for most of their existence.  With roots in the kind of music that couldn't get played on the radio in the early days, rock was destined to be about challenging the status quo, and consequently, its adherents tend to follow more extreme ideologies.

Not to say that there aren't conservative, secular rock groups, but like most entertainers, they're marginalized.  Or at least far less vocal than their couterparts.  With the possible exception of Henry Rollins.  Who's more of a independent probably, than a true ideologue.