Well... it depends, if the pictures they posted was not in any way with the intention to perv the Buddha image, then logically and also based on my sole opinion, it should be fine.
However, when one visits a foreign place, it is after all wise to be more attentive and sensitive towards the local culture and respect that. In this case, being in Sri Lanka and surrounded with conservative people, it should be correct not to do something out of the ordinary such as kissing the Buddha statue.
I do not think the French tourists here are in the wrong, but I do think that they were not careful or sensitive enough towards the local culture that is conservative, therefore the outcome of such ignorance is this.