I agree with the responses above!
If Katy and her team informed YouTube that they wished for the editing, or if YouTube informed them that the editing will have to be done is a question which remains open to me, and I wouldn't take either for granted without a statement from either, but it was done 1. In Katy's interest, 2. in her fans' interest, 3. in the interest of YouTube as a business.
If Katy suggested editing in the way it's been done or not, either way she would agree to the now status quo; I think it unimaginable that she would wish for reversing it, and by signing the above mentioned petition I'd act against her interests (no matter how futile such a petition may be anyway).
Nobody was forced, legally or otherwise, to do the editing, but somebody, whoever it was, decided it was to be done for good reasons.
For Katy the change of a small detail like this one is certainly meaningless; if I had watched the video many times before and many times after I couldn't have noticed the difference. If that difference is so important to some weird people, be it because they're religious fanatics, simply stupid trouble stirrers or for whatever reasons, that should be meaningless to us, too; imagine what a sad life they must have!
I believe that the person who suggested to hang all those pendants on the actor's chest didn't know what any of them means; Katy didn't chose them, and wasn't aware if it either - but it is Katy who has been aggressively accused and abused for desecrating a sacred symbol where in reality she hadn't even noticed there was one. To stop that misguided accusation is the main reason why it was removed from the video image, and that should be understandable.