I think what really happened is that Urban Airship discovered the SimpleGeo service was really crappy and decided it needed to shut it down as soon as possible to avoir eternel peril...
SimpleGeo has rewritten its platform several times (project GISele, then project Penelope), it was done by people who thought they knew how to do geosearch, but they really had no idea, for example they never offered polygon search, they also only offered tag search a few weeks prior to being acquired, and it was done by a girl who left the company like a week after her feature went live.
This company was probably a scam from day one, it only got money because its founders were reknown.