I don't think the sloganeering is hastily thought, I don't think it is thought at all. It doesn't need to be. Freedom of expression ingrained in Western culture and you would find it very difficult to believe someone should be executed for expressing an opinion. Fined, jailed, maybe, but never executed.

To think of 'I am Charlie' as supporting the cartoons themselves would require you divorce the victims from their fate. Essentially, you'd have to make a leap of logic, and focus on the selfish part (i.e. they offended Muslims) and at this point you no longer deal with rational argument.

Essentially the devil's advocate argument is 'a mature and reasonable person should practice caution before saying anything that may be taken out of context by any party that is sufficiently upset', which is nigh impossible.