Fair play, I much more prefer FP rather than a "F U".

Fair play would be for the person making the claim to ownership to front up proof of ownership and proof that the source has all the required credits and or rights.

Only after that can they expect fair play.

Flanking someone with accusations and not supplying any reliable proof what so ever is literrally FUing the entire idea of the link you are refering to.

It works both ways, it is a two way street.

Likewise: If a photographers name was not listed as per the laws regulating this topic, then the person making a claim does not have a (legal) leg to stand on.