Any rear ender is 100% the fault of the car that hits the front car. The rear car should have braked to leave at least a car's length behind you as they would see your car merge in.

I hate that section (Holdom and Lougheed). When I lived on the mainland, people always blocked up the right lane to get to Starbucks and I saw a few fender-benders like this back then (2006-2010). If you're trying to get back to Canada Way (which was what I was often passing through there for), it's best to stick in the left lane until you pass that commercial/condo building.

^ I agree.
Anyways, he can take this as experience and a lesson learned.

Honestly that spot is absolutely terrible for those types of accidents. I work for the city and drive a f650, literally everyone tries to pass me at that exact spot (Lougheed & Holdom) and I manage to stop even with less space. Definitely not 100% at fault at all