It's a normal tumblr thing.
From what I see, when they get called out for "abusive behavior," they usually yell, "You are abusing me by saying I have abusive behavior due to my BPD/HPD/AvPD! You are the problematic abuser, not me!"
They do the same thing with being a minor. They're apparently allowed to send death threats as long as they're a minor. When it's brought up, they think "Oh, I was 17 then, so it was clearly okay for me to do all those bad things." And of course, once they become of-age, they twist it by going, "I know better than you, so I am right and you are wrong."
Tumblr also has a weird fetish for having tiers or ranking for disorders. I recall reading posts where they stated that having severe anxiety as a mental illness doesn't "count" because it's not as "big" as other disorders like BPD. They have a hipster-mentality when it comes to these things. For example, they find that depression is "too common," so they disregard it and try to find more severe disorders to glorify (and use as a get-out-of-jail-free card when they inevitably mess up).
The entire site is just a bunch of mental gymnastics in order to excuse themselves from any actual responsibilities in regards to their actions.