(((Greet)))
You ask such good questions. I can't guarantee I'll have good feedback, but it'll be unique to me and my odd world, so...
Being a contemplative sort of person (in fact, I earmark a section of every morning just for thinking, writing, and meditation) I found that a certain form of meditation called "metta" helps me a lot.
I'll start by sending gratitude to myself and my instincts. They are there to protect me, and they are good. They're also almost always right - there's a reason why you have the creeps, in other words. You're sensing or smelling or hearing something that is deeper than just the person's overall disgruntled state.
I'll think about what's important in the situation. For me, the work I do is truly a labor of love. I love my work and am very protective of it. Is this person's attitude interfering in your work group's ability to create the message/product/result that it wants to create? Your inventory-taking could be your inner champion, your inner Artemis, saying, "Hey, you know what, this person's attitude is damaging our best efforts." Give that some airtime. Is it time to recommend, kindly but clearly, that he no longer be involved because of the energy drain he places on the rest of the team? That's perfectly legitimate. I have fired clients who simply brought too much baggage and too much bad juju to a good and honest effort.
And the metta part -- metta is a Pali word that means, roughly, "loving kindness". You practice it, even a couple of minutes at a time, by sending out love to people -- ALL people. You start with yourself, give yourself a deep mental bow for even having the compassion to begin this conversation. Then move on to people you love. Send them a wish that they will find the guidance and peace they need to become better people. Then you can work on acquaintances, strangers, and finally, people you don't like. Send this guy some love, some optimism, some willingness to see things differently.
All of us deserve love, no matter how lousy we are being. Bad behavior comes from deep inner pain and fear....and the world can only benefit by sending more love splashing around.
Anyway.....a couple of centuries of that and I should have it down
And if none of that works, a direct confrontation always works. "It's not really productive or necessary to take that perspective, and it's damaging our teamwork."
Greet, you're wonderful!
GiveLove