I agree with this opinion in concept. However, in a case of alleged murder, if by some chance I got potential evidence, I think I would have turned it over to the investigators and stopped there.
Because if it really is evidence, providing it to the media is an attempt to involve oneself and then claim anonymity. Either you stand behind your picture or you do not. If the person provided it to Investigators and it ended there, I'd have less question about motivation of the person who took the picture.
But we don't know that if it hasn't been turned over to investigators. It's been speculation one way or the other based on the line in the article that said 'investigators are aware of the photo'. People can spin that line either way but unless LE comes straight out and said 'yes that photo was provided to us', we really don't know if it was provided.