This isn't a triple A title and when it comes to translating programming time : playing time, then replayable minigames will be, more often than not, more efficient than tweaking or polishing the main game, especially in the platformer sector.
In the end it also comes down to personal preferences and the individual design of the game or minigames.
If mofu really plans to put a fix finish on the game, then it won't make much sense to add a minigame at the very end; barely anyone will profit from it, as most won't return just to play a minigame; while the other way around it will definetely work; most people will come back because they want to play the full game.
My suggestion would be to prioritise the minigames by the necessary effort to create them; he could add the biggest effort minigames at the very end, within a huge update, which will also end the last quarter of the storyline (once the game mechanics are stable and fix) and the easier-to-create minigames before, to keep the game interesting and the community attracted.
(And also to add a public to-do-list, perhaps...) so people can comprehend better what's still to come and what not and whether it makes sense to make a likely trivial suggestion or not.