Uploading Guidelines said:

Important to note, we still allow “fan edits” but we will remove them if the artist wishes so and we may take action against the editor if the edits continue to be uploaded after the artist has asked to stop them.

That wasn't a fan edit, you hatefully edited the picture cause it wasn't to YOUR standards and did an edit just to appease yourself (@ Knob Dole).

Same could be said about a piece of literature being made, someone goes copying it then retype parts they dislike, and redistribute it without changing the title and put their name in with the original author. What makes you think that first artist wants to be lumped in with the second one cause the second clearly doesn't agree with the first.

And to answer why MLP art is considered acceptable as in term with Hasbro, it is a parody tribute to the original concept, which has been openly considered accepted up to the limitation that you don't claim ownership and you don't label the original company for being the one who did the parody, just the source from where the material derives.

Hopefully I have made myself clear cause I'd rather not have to go into further details.

Truthfully, you should have just made a piece from scratch and it could have avoided all this to begin with.