The presumption of innocence is a pillar stone of Canadian law.
To this point there has been nothing released to say that they are anything more than suspects, and should be considered dangerous.
Using Steam, playing with airsoft guns, and racial background are not permissible as evidence of murder in court, only premeditation, if that. Even if they are killers there is a perfectly reasonable explanation for all of these, including the fact that they are teenage boys.
Before Steam it was dungeon and dragons and magic the gathering. Just because you don't understand something a younger generation likes to do for fun, doesn't make it proof of premeditated murder or genocide
I've noticed on twitter that the everybody is considering them as murderers, which they MAY be, but so far they only they only suspects. As such, the jump to genocidal maniacs is a massive stretch, at best.