So what's the tipping point here for the Bruins as far as ppds/cancellations? It took 6 players before Calgary cancelled their next games, now three after they added 17 more.
There's no hard and fast rule. They seem to take each situation on a case by case basis. Part of why Calgary got shut down quickly is because in the short term they were supposed to play games in the US. To be honest, I'd rather be Calgary and have everybody get it all at once which forces a shut down than the slow drip of a player or two a day for a couple of weeks.
I would think internally the Bruins traveling party has serious reservations about the trip this weekend. I'm not sure if that's being factored in, or if they or the team has voiced concerns to the NHL/Players Association. They just implemented enhanced protocols today which means daily testing is back (had been every 3 days up to now). If they are forced to travel, there's a non-zero chance that a player/coach/staff member tests positive while on the trip and then gets stuck in isolation for 2 weeks in Canada, mising being home for Christmas. We have a veteran heavy team, many of which have young families so I'm sure they wouldn't be enthused about this possibility.
Another factor that works against the Bruins is their stupid fucking schedule. It's back loaded so there's not much room in the back half of the season for makeup games.