-- that was a joke. My point, which I addressed further below, is that I think it's a reach to align this with The Last Supper before all the other things it can be more obviously aligned with, including what it was actually representing. At minimum, I don't understand responding to this with a surety that it's definitely mocking Christians. Seems very unlikely for France.
I do think the offence is based on a misunderstanding of the intent and a lack of interest in exploring the intent before reaction publicly, which I think it something that's just way too common. People can be offended by very nearly anything. It doesn't immediately follow that they are being reasonable.