Yeah I suspect your GM is... not really knowledgable about Shadowrun's world.
The players think its a Cyber Ghost named Ed. Doesn't mean that is what it actually is. And every GM should do something to expand the mystery of the universe. Nothing is more boring than knowing everything in a game.
Tough to deny the GM having the thing communicate with them, save them / bitchslap them, that sort of thing. It
is possible, of course, just more than a little weird. And here's the thing - we, as players and especially as GMs, SHOULD know most of what is possible in the game - especially in the non-magical world. If the van was possessed by a
real ghost, then you edge into the unknowable. The cyberghost is ... on the edges of what we-as-players-and-GMs know as being possible.