Do you even know the history of this game?
He has been developing that thing since at least 2019, this is not a "vanity project" to "gain some experience for the next project". He wanted this to be a genuine game, with more stages then the 5 he wants todo now, with actual debuffs and puzzles that affect how you progress through the stages as well as a story to go along with (which he always included, but MTL ain`t the best to enjoy or even understand it).
But the programmer he got turned out to be not that good, which is why the foundation of this game is so brocken, causing most of the bugs.
Canning it would have been the best option, but at the time he realized that he wasn`t able to make the game he imagend, he had a bunch of followers and a 600 yen paid plan, which is even today above average of what most devs normally set.
That`s probably why he keeps the game juging along despite it beeing so brocken he doesn´t even want to playtest the thing. He doesn`t want to kick the people in the balls who have been supporting him for years or atleast doesn`t want the bad reputation that would have come, if he canceled it.