All of that is true I’m sure N90 but at the end of the day we (the industry) don’t want to go too far down the road of pilots thinking that declining a heading is going to cause a gigantic headache for them ( this pilot probably has a headache by now). If the pilot had felt it was better to fly through the cell than increase the controllers workload, and as such accepted the clearance, and picked up hail damage and injured pax, we would all be wondering why he accepted the heading. We’d be saying things like “ who cares if they have to halt departures, just keep the aircraft safe, the controllers there are the best in the world they’ll conjure up a plan “.
This is really a storm in a tea cup in that nobody was hurt, two blokes got a fraction shirty with each other, job done.