Uneducated investors look at outsourcing as a cost reduction move because, in most cases, they don't know any better. There is no way that outsourcing their IT operations will save them money in the long run, but it should help to boost the price of the stock.
Further, the "retention" bonus is no such thing. You only get the bulk of it only if your position is transitioned to the outsourcing company. All they need to do is say that they aren't transitioning the position, wait a few weeks, and then offer to hire ex-employees back at reduced wages.