"capitalist pig" that I am, I tend to be cool with whatever willing buyers/sellers agree on.
Ours is a free country, of course, but IMHO this "intermediary" is not adding any value whatsoever. To the contrary, he is likely just messing up the future of this Monaco: she was a nice example for someone to fix properly, even if the spring 2021 price under prior ownership was already only borderline reasonable (the interior is cooked). Now, the likelihood of such a happy (for enthusiasts) outcome is IMHO much lower.
I get that some people need to make a living, and I agree that some flippers do provide value. For example, if someone finds a car in a barn of which no one was aware, then cleans it up, and ends up making a lot of money -- more power to them. They have spent their time/effort/money
and taken monetary risk to get the car into the hands of someone who values it (and would otherwise never have had the chance to save it). In the present case, though, the car was well known already and no improvement has been made, so I fail to see what service is being provided. The $15k asking price increase is a lot of money for a few hours spent acquiring the car, stuffing old sheets as headliner and car covers, and getting it re-titled (in fact, the latter action adds an owner to the ownership sequence, which decreases the car's value).
Capitalism, no problem here. Just don't expect me to sing this flipper's praises for his "work" to date