Unless he felt the picture was in some way inappropriate (I don't think it is at all and would be acceptable on IG if she wanted to post it). Maybe he mistakenly clicked a downvote or felt the rewards were too great.

I also do not understand the reason for the flag and feel the flagging system should at least require you to pick a reason why you flagged content, because if @dantheman does not leave a reason for his flag, @katecloud has no beneficial feedback as to why she was flagged in the first place.

To me the flag should be used to help change something you feel is spam or mislabeled or hateful, but some use it to give users less rewards, which is their choice, but to me not the best use of a flag/downvote.