I agree it was dreadful too and I personally just pretend it never happened, lol I think it is unanimous, but I just took the last one's story line and plopped it over here so... I would just see Geth and Reapers being birds of a feather both mechanically and so why wouldn't some sort of subsonic blast or what ever that was effect Geth too along with all other mechanized sentient beings? But for the sake of keeping things simple lets just say get, AI systems (such as EDI) and the Reapers were affected by the blasts, keeping the argument of all of the galaxy's forces stranded in the Sol system. 
If it really bothers you that much we can just say a fleet of geth at the edge of the veil or exploring the vastness of the Veil were not effected by the blast from the Crucible.