I'd say it was 50-50. You're right that McLaren shouldn't have created the situation in the first place, but Norris also needed to give the position back much quicker than he did. Norris really was behaving like a petulant child, not someone supporting a team member who has had his back on countless occasions already.This is 100% McLaren team problem, not a Norris problem.
This situation should have never happened.