I think the elephant in the room that isn't getting much discussion is Harvinger owner Rob Post. I purchased a bunch of resin parts from MAFC over the years and Rob always made it super clear that he couldn't give a shit about customer wants or convenience. He ran that business at his convenience and he was very up front about it all over his website and newsletters. I think the Soup Nazi is an apt comparison. He would produce a limited run of something and once it sold out, it was gone, maybe forever, and he had no tolerance for questions about parts being reprinted, questions about when orders might ship, or questions about commissions. I wouldn't say he was an asshole, but the only customer service he wanted to engage in was sending you a replacement if something arrived broken or wrong.
It sounds like he makes pretty good money as a consultant for a major accounting firm. I'm sure he doesn't want Harvinger to go into the red, but he doesn't need, nor likely wants, Harvinger to blow up in size, either. As has already been pointed out, this business is still just a hobby for him and the cap on production numbers is probably more about keeping the company small and manageable than the financial appreciation of the toys they produce. Whatever money he's "leaving on the table" clearly isn't worth the hassle for him.