Well, if you are assuming people can SDI/DI with regularity, then you might as well expect people will understand the grab release mechanics as well. You have to be right over the edge to ever force an air release on spacies or else they can just get released on the ground and with enough room not go offstage.
Anyway, it'll be harder to time grabs. It's only out for 2 frames starting at frame 8. Jab hits for 4 whole frames and starts 5 frames sooner.
If any spacie gets to the ledge after the jab, just expect it the next time.