Morally wrong? Quite likely.
Illegal? Nope; Charlie Hebdo has the right, and the guts, to publish whatever it feels is a pointed comment on the foolishness of a State which is busy attempting to bomb IS, a terror organisation, whilst complaining of the ‘sacrilege’ of Charlie’s depiction of jet plane parts from a ‘cowboy’ and ‘cut-price’ airliner falling down on an IS terrorist.
If a few more main-stream newspapers and screen-based publishers showed that they too would not be terrorised into a virtual ban on depictions of this clown Mahommed, whoever he may or may not have been., I reckon the world might be a more healthier place.