i feel like it should be obvious but...when we say "boomer" we're referring to a mindset. If it were really about age, there are a lot of people older than boomers we could be calling out. It's not about age, it's about this culture of systematic discrimination and failure to hold people accountable for the ways they treat other human beings that many of us are just 100% fed up with. There are plenty of actual boomers age-wise who are also fighting the bad stuff, and they don't make it about them because they know it's not about them.

Boomer isn't a slur. It's only even an insult if you're part of the mindset it's referring to when somebody uses it that way. It's not "haha that person is older than me and I don't like old people!" it's largely "oh great you're another person who thinks that everybody who ever remarks on the ills of society is just a whiney baby and who thinks they should be able to say or do anything they want without these obnoxious politically correct crybabies calling me out on my discriminatory behavior."