I take no real pleasure in saying this but I think the arrogance is in his character and was there from day one.One of the basic lessons of working life in any profession is that when you leave a job you should try to "shut the door quietly behind you". You never know when or why your former colleagues might be of help to you.
It does seem a shame though. No doubt sometime in the future there will be some kind of reunion of the squad from that era, but you wonder whether Tisdale would be there. All feels a bit unnecessary and easily avoided if he had behaved less arrogantly.