This might be a bit of a weird one, idk. I'll try to have this make sense as best as I can.

My friend and I are both part of a hobby community which involves a lot of arts/crafts type of stuff (lots of painting, model-making, design work, use of fine tools, etc). I've always been pretty handy with this sort of thing, and my friend and a few others have come to me periodically asking for both help and commissions on various projects they want to have made. I usually accept, either for a fair trade or I'll do the work for free for them, so long as I can do it on my own time. The friend in question is someone I've been making models for and giving advice to since probably 2017 or '18 or so. He's usually been grateful for the work I do, but he doesn't have the skills, tools, or practice that I do, so whenever he does make his own work, it's usually something very minor and easy to do. That's fine; I've never really had problems doing the more complicated work for him, and I've encouraged him on ways to grow his skillset.

Anyway, he recently decided to take on a project on his own to replace a pre-fabricated model part with his own version. I didn't know he was doing this, and he didn't come to me for any tips or advice. Well, he botched the job so badly that now he has to order a new model shell, which isn't cheap. He posted pictures of what happened in a group chat we are in with several of our other friends, also noting that this is the SECOND time this has happened, but that he tried the same process with a few other models and it seemed to go better previously. I've been to his place numerous times and have seen the craft equipment he has on hand, and most of it is fairly cheap and low-quality. Usually, that's okay for what our hobby requires, but he also never cleans or organizes any of his equipment, so I suspected the botched cutting job was a result of poor blade quality. This is also a project I've done on my own numerous times and always gotten clean results, so that's where my mind went first: diagnosing what went wrong. The following was our conversation as it happened in the group chat.

Me: "What exactly was your method of getting this off?"
Him: "Using a hobby knife to pop the [part] off"
Me: "Show me your hobby knife."
Him: "You've seen it before, numbnuts"

*Note that the last time I saw any of his equipment was likely over a year ago, and he's used it for other projects since then. Anyway...

Me: "Yes, and that might be part of the problem. That’s why I want you to show it to me, genius."

*I'll admit I shouldn't have retaliated with the "genius" sarcasm; that one is on me to own up to.

Him: "How? It's literally the same hobby knife."
Me: "Because I want to see what blade you're using."
Him: "If you’re going to bitch about it being dull, I used the same one with [other model] and there were no issues. Literally it’s because of [botched model] and how it was glued to the model"
Me: "That may be a factor, sure, but it’s going to be the same glue or cement used across both models, just possibly in different locations. Since you mentioned it being the same hobby knife I’ve seen before, the implication in that statement is that it’s also the same blade as the last time I was there. This is a sign that you’re not changing your blades often enough, not just a sign of difference between the two models."
Him: "You really love playing with fire don’t you? It’s literally the model, not the knife. Get over yourself."
Me: "This isn’t a personal attack, merely a problem with either the model or the equipment you’re using. That has nothing to do with you, but if you’re going to get upset with me for trying to diagnose a problem, I would want to know where that is coming from."
Him: "Just another one of your usual ways to undermine me. But whatever, I’m really not in the mood right now"
Me: "I’m not trying to undermine you; I’m trying to help prevent this from happening again in the future. I’m not blaming you for what happened here."

That was the last point we left it at before the conversation moved elsewhere, and none of the others in the group have said anything about it. I don't know what exactly he thinks I've done to undermine him, considering I am someone he routinely goes to for both modelling advice and commission work. I'm wondering if I was too upfront with this or if I should have handled it differently, but this also isn't the only time he's gone on the offensive against me for issues that he has started. It's getting to the point where I'm questioning if this friendship is even sustainable, or if I'm just overreacting and should let this go. AITAH?