I don't consider Halo:Reach as canon think bungie should have gone
with First strike, maybe as Red Team and a couple of mission as Chief
in operation first strike. Would have been a nice introduction for Fred and the Brutes first encounter..
I want to consider Reach canon, even though Bungie made it pretty difficult to. Don't think they needed to translate book events to a game, but they could've told their story in so many ways that didn't conflict with everything pre-established.
Considering the attitude the Bungie higher-ups seem to have had towards Halo's expanded universe, though, it's not very surprising.