He does this a little to me, but far, far more to others.
So questions:
1) Does this sound familiar?
2) how can we get him to relax the defensive barrier once built?
3) How can we avoid provoking the defensive response?
4) Can he be taught alternate ways of responding, that are less destructive to teamwork and communication?
1) I can be very stubborn when I feel I've been wronged. I will, in my head, go through the 'fuck them' script and mentally discard them from my life, only to have them reach out, we talk it out, and all is forgotten. I don't hold grudges unless you have wronged a dear loved one, or tried to manipulate/use me. Then, I'm focusing on setting up the steps to best deliver my 'poetic justice' to said person.
2)-3) IGNORE! Cut off the very context that allows him the
reaction of shunning in the first place. He knows his position within the company, and the asset that he is, if he is an unhealthy ENTP, he is getting off on seeing so many people get their panties in a knot through his assholish behaviour. It feeds into his ego that he's causing such a domino effect. Stop feeding the beast.
Give the most minimal feedback to him and his ideas when presented in such a deliberately rude manner. And, give positive reinforcement once after a few of such 'misses', he starts warming up (i.e. appealing to their logic, in a way that feeds their ego/affirmation of their ideas). Do not try to tell him why being polite, etc., will work in his favour. The very act of telling him, will make his unhealthy self rebel. Let him 'find out' for himself (and guide that process). Also, being polite as a means to an end is more (than likely) the ENTP's (unhealthy) cup of tea, hence, only end result consequences will work.
Finally, if he's a true ENTP, he will need that external feedback, things to bounce ideas off of, direct you OWN behaviour so that you engage that Ne of his ONLY when he's not a prick, otherwise, offer him silence. Take his idea with barely a nod, and just implement, no other positive reinforcement (it will make him realize the parallel of why when he receives a work from another, without acknowledging their effort, may seem harsh).
I.e., allow him to modify his own behaviour (be a guide only as far as you modifying your own behaviour accordingly to allow him a clear cut negative verses positive reinforcement), do not put your hand in the lion's den, you will come away more harshly bitten, in your aims to soothe and pet, than you went in.
4) Get the team to follow through not appeasing him. When his feedback loop is depleted and he associates
that as a consequence of his own decorum/behaviour (repeated trials giving same results - reliability testing), he will change his ways, or leave. Either way, it's not going to do any good trying to get an unhealthy ENTP balanced through others intervening, we're fiercely independent, and we smell 'manipulation' like a lion smells blood. It will not end well.
Control
your own feedback you give him in the direction that you want the change. I know being Ne+Fi, it's sometimes hard not to intervene in making someone better their inter-personal relationships for the greater good of all, but, cut yourself and your own motivations out of it. You will be much more successful in helping him. Otherwise, he will quickly tire of your 'giving good advice' ways.