The most fundamental tenet in wingman role in an EP is: don't be a hindrance. The broken aircraft generally takes the lead while wing supports. That means you STFU until you're needed by the EP jet. The only time someone would be steering an EP resolution from the chase position is if the broken aircraft is being flown by a completely unqualified student (hence my comments about the "UPT style talking to" that clown was giving the non-participating Arrow). But that's in the context of a mil environment where everybody understands and has been exposed to the expectations and standards that define this kind of flying. Appropriating that behavior into a foreign environment for the sake of a self-employed CFI business shtick is not only insufferable, but replete with real pitfalls. Bringing that whole mess into a non-participating civilian aircraft no less? That's where it goes beyond clownish and into the realm of the FAA, especially if the Arrow had got distracted and bent something.
So I don't even want to give this clown that amount of credit, but from even an EP resolution perspective on this side of the fence, he broke the cardinal rule and would be getting a roasting at the squadron after he got down. The guy legitimately became a hindrance to the Arrow, and almost made a manageable situation into an accident by proferring unwarranted inputs and self-appointed flight lead over the EP aircraft, on a non-participating basis no less. Again, I am completely astounded by the amount of rope tower allowed to be unwound on this circus show.
Tell your homeboy that he's not the only one in GA with prior mil experience. His judgement is severely lacking. Being a good stick doesn't at all mean you're a good pilot. We have a few decent sticks with poor inflight judgement. Usually as a function of inexperience, but sometimes we have senior pilots with a reputation because they can't seem to make command judgement decisions without causing drama at the destination and always getting a talking to. Some happen to be cavalier in their flying, which only lasts so long before something gets bent. Your buddy looks like he has something to get out of his system or needs closure from not flying in the military anymore (if he ever did...hell who knows, we just found out about a prior enlisted flying Mirages on a merc basis in Lybia with zero mil flight training, so anything is possible these days).
Tell your friend to knock it off with the UPT appropriation shtick. Remind him he's no longer in the military and the FAA doesn't appreciate impromptu UPT syllabus implementation and mil student pilot procedures being used in the middle of non-participating class D airspace. Also remind him he's not at the B-course, and thus flying chase on your initial solo PPL student is a complete d-bag @ss-shining for YT clicks. And finally, I would ask he invest in some aerobatic aircraft and get whatever hangups he has about not wearing a G-suit to work out of his system, for the sake of his clients. Whatever it is he needs to work through to let go of the military training pantomime he's passing off as "experience" to overcharge his customers. The internet is a pretty wide lens and we're all watching. It's embarrassing best case, he's gonna hurt a client worst case.
As to the white knighting on your part, remember.... the road to hell is paved with good intentions. This guy is likely to dismiss anything coming from the internet. He needs a friend, hopefully someone with military experience, to tell him he's being an @ssclown. Friends don't let friends be @ssclowns. Don't enable @ssclowns.