I remember once when my friend reblogged one post that was exclusionist. Like 10 minutes later he deleted it and apologized saying "holy shit I didn't realize exclusionists were such assholes. I agreed with one thing someone said, but when I checked out the tag I realized... it's messed up." I think sometimes exclusionists get so far gone they don't even realize how they appear to the rest of tumblr. Hateful and violent.
I actually wrote a thread about the parable of the frog that gets slowly boiled alive by people slowly turning up the temperature. That’s absolutely how abusers get excused. And in this case I think casual REGs of any sort just turn up the heat just a little when they reblog stuff like that. They think well that one thing isn’t a big deal. This one comment seems reasonable and they really don’t realize that collectively it empowers very hateful and very violent people.