(An aside before I start: I am totally going to call some superhero plot device the "apocalypse engine.")
I don't own any games that are powered by the Apocalypse (PbtA), but I will--I've backed Masks and I'll get a copy of it sooner or later. But I see comments about it, and about Worlds in Peril. And this question came up, along with an answer (and of course I can't find it any more...the title was something like, "How to Ask Nicely in DW").
But the answer suggested that there is no just-riffing move for the GM. If the players asks for something (the title You don't do a simple information check. What the GM says has to move to story forward: say yes, introduce a villain, make a conflict out of it.
That's very much the improv "no blocking, no wimping" rule. Whatever you do, it matters.
It's interesting to me that you restrict the GM in this way. (Presumably you also restrict the players....there's an SRD for Dungeon World, isn't there? I should read it.)