Wooba, I may be missing some context on your sitch, as I'm only responding to your most recent post. Feel free to let me know if I've missed something about your dynamic.
In point 1, I think you put him on the defensive. He shared a thought (very, very poorly) that was on his mind. Absolutely agree he likely did it in a passive aggressive or non-committal way. But you then bounced it back in a bit of an accusatory way instead recognizing (validating) the fact he had a thought. You blamed him for mumbling. What if you had instead simply very calmly and curiously said, "I didn't catch that?" or even, "sorry, I didn't hear you".
I often find myself saying to folks, "sorry?" when I don't hear what they say. Of course I'm not really "sorry" in an apologetic way, but it's a prompt. In this case I can sense your frustration in his mumbling, so saying "sorry" may feel like you're conceding something to him. The wording is up to you.
And on point 2, why does it matter that you let it slide? I'd say that's the right move. Let H stew in his mis-aimed frustration. He was wrong but you don't need to continue to point it out to him. He got it when you clarified. And then he was still frustrated because he was wrong.
In these two instances I would not call you conflict-avoidant. Perhaps in other areas I am not caught up on. But sometimes it's best to let them stew in their own anger and not engage or try to take ownership for it. It's not your deal.
