Personally, I wouldn't read too much into that.
As an experienced Canon shooter I find it much easier to help someone who has a Canon camera; sure, the principles don't change, but at the end of the day (a) any equivalent camera will do the job, but (b) it's just going to be a LOT easier for the tutor to navigate menus and set modes (knowing their effect). So it's not a dispersion on other brands (not saying "Canon is better") just a case of "why not go with Canon if that's a factor that tips the scales". Sure - it's no "better", but on the other hand, it's no "worse" either -- so why not just run with it.