It is impossible  to move a coin by mistake meaning if that coins moved meaning it is Satoshi that act on it and as you asks about what would happened, then for sure the market will have its big movement , depends on how the community evaluate the meaning of that said movement.

because this can be resulting to Dumping as many will secure their money by selling the bitcoins , or the other scenario is that people will keep buying because of assurance that Satoshi is still alive and kicking.

Not unless there are other entities that truly has access to that funds and from that things will have different result.