People do not always give the reasons for the refusals, but they do sometimes. I have never heard that reason but, yes, if I thought that it could be true, it would give me the shivers. I have talked to people I call immigration rules consultants. We have three of them in our little team. They have told me that they have heard rumours along those lines.
We tell the applicants that they have to explain why they want to do their studies in French outside Quebec. Our suggestion to them is that they say that, of course, they want to study in French, but they also want to develop their skills in English. When they come from Africa, our students often speak several languages, but English may not be one of them. So we ask them to explain that in the cover letters they have to write.