I'm not buying that either. Maybe it was thoughless to call Kirk that, but Wesley knew if M-5 worked flawlessly--a LOT of people were out of a job. So the dunsel comment was kind of a rueful way of saying "we're all obsolete."
I think we are really seeing to different interpretations. I think you seem to think Wesley regards Kirk as an equal, a comrade or even in a tight knit club, not really a personal friend but in the same boat on the obsolete issue. I may be wrong with that assessment and I'm not trying to tell you how to think.
I see Wesley as thinking he's clearly above Kirk. Yeah, too bad for you Kirk, but I'm still going to be at HQ ordering fleets around. I think he looks down on Kirk the whole time, "it's a real honor Jim" I don't equate the colloquial nature and first name basis for friendship, just a cordial working environment. Look at how puzzled he was Spock knew all about it. He was the cat with the canary until Spock started it, lording it over Kirk. I don't think he hated Kirk in any way, just that he's better. Just look at the reactions of the bridge crew. I think Sulu and Chekov were both pissed, and Spock the emotionless guy, he really didn't like it either. If he said that in a bar, someone might have hit him, Commodore or not. I actually thought McCoy denseness was up too high, I think he could have done with out on or two "what does it mean"s but no one wanted to answer in Kirk's hearing because they didn't want to repeat the insult. That was quite an insult. A slap in the face for a guy like Kirk.
So, I think that's where our opinions on this differ. He is more willing to blame a subordinate for failing than the equipment.