I was on this mornings flight arrival into LHR from IAD when on taxiing to the stand the pilot had to make an emergency stop which threw everyone forward in their seats.

Had the situation you described been happening without any doubt anyone standing would have been thrown off their feet, and had they been pulling luggage down at the time that would have landed on someones head.

Sounds like CC made a judgement call, but with possibly serious consequences had they made same call on my flight this morning...