Honestly? Jin and Jimin are /adults/. They’re not catty teenage girls going behind each others backs and insulting each other, this was a part of a /game/, where the point is to roast someone basically.
Obviously, no one is trying to say that the statement that Jin made was okay or not uncalled for in any way (it personally made me cringe, and yeah, I’d rather it not have been said). But to criticize those kinds of statements means you should criticize them when they’re being used against anyone, including the /countless/ times they were used against other members i.e. Jin.
Going back to the adult thing, Jin and Jimin work and live together, and have for almost 5+ years. All of the boys are very close, and if there is an issue, I am sure at this point they are mature enough to address it with one another and talk it out.