So, background on the way tumblrs gif embedder thing works is, that you can use it to natively include a specific gif from a specific tumblr post by url, ONLY if it is the exact first gif on the post.

I didn't even know that. I usually just post text, embedded links and embedded YouTube videos. But the technique you used sounds perfectly reasonable to me.

Also, don't forget that we (on Tumblr) are the queer, autistic website, so a few people might have extreme reactions to certain things for reasons that we don't know (maybe they were called out about it by somebody else and are continuing the calling-out cycle?). Try not to take it personally. *hugs*