I could see some outside shot of -any- Summon backfiring that way, especially if caused by magic and not divine powers. You mess around with the dimensional boundaries near your target, something goes wrong, and it ends up being you moving, not them. Maybe in those rare instances it becomes a contest of smarts or something between you and the target, and the loser gets moved.

That would be fine, and might create some drama involved in using it. However, tacking on "This happens a lot if there are people around you, but it doesn't matter if people are around them. And, oh yeah, only PCs seem to metter, and not NPCs." smells very artificial. We might as well add things like:

You try to summon Beefchunk to where your group is standing.
A big fist appears and punches you all in the groin! OMG!

, if we were just interested in arbitrarily abusing the summoner without creating a chain of logic behind it.

valguarnera@carrionfields.com