Seems likely. I've seen plenty of people say "Oh, this old-ass Boomer thinks [whatever shitty opinion here]." And this is in direct reference to people in their late forties/early fifties. And if you correct them and say "that person is Gen X - they're the child of Baby Boomers," they'll pivot to "well, Boomer is a mindset, not age group." But it does seem more likely to be an insult for old people or people who appear to be out of touch in some capacity.