Hate speech: Noam Chomsky signs petition against Gassot law application

Chomsky is not a supporter by any means of genocide denial, the crime in question under the loi Gassot of 1990, but finds laws preventing the challenging of historical truth offensive. Contrast this with the use of genocide-denial laws in Rwanda to silence opposition to the presidency in the recent elections. Can genocide denial speech be prevented by imprisonment in a free society?