You can do swap operations during rapid pausing.
In this movie, I enable redraw flags for all rooms, and the game fails to update some VRAM in time.
But this glitch only affects drawings, so I think it is not so useful.
EDIT: Probably you can corrupt the PPU transfer queue ($0400-$04FF, typical ring buffer) with this technique.
For example, if you write a length=253 entry to the queue, the NMI thread will loop infinitely.
But anyway, I think it will be extremely difficult to take advantage of this for TAS.