The government of Quebec will not grant him citizenship ever because there is no such thing as Quebec citizenship. Quebec is not an independent country even though they like to think so sometimes. Quebec is a part of Canada.
The Quebec program as well as all provincial nominee programs make people sign documents stating they intend to settle in that province. If you never attempted to settle in the province, they could theoretically go after you and say you lied on your application and should lose your PR. However, I have never heard of that happening to anybody. Still, it's safer to at least stay there for a few months and look for a job. If he finds a job, he can stay longer, if he doesn't find a job, he has already tried to settle there and can move on and look for a job somewhere else. The Canada charter of rights and freedoms states that Canadian PR's have the right to live and work in any province.
There is no minimum time listed that he needs to stay in Quebec. If he wanted to be 100% sure he will not have any problems with them, he should stay for 3 years, apply for citizenship and continue staying until his citizenship comes through.
