The reason that Quebec residents are excluded is not solely a language issue...

The governing body which regulates contests has very strict rules and consequences, designed to protect residents. They require such issues as posting securities for prizes, letting the government mediate any dispute in the contest, paying the government a high upfront fee to even post the contest, etc.

You should really look up the rules as they are quite eye-popping and the main reason why most sweepstakes exclude Quebec.