I'd be surprised if the Sony news had anything to do with this. These sorts of acquisitions don't happen overnight, they've likely been talking for months, doing due diligence and other research into the deal.
They were almost certainly in touch before, but the deal being done in 5 days means that the sony announcement could have been the event that pressed the oculus team at look at an acquisition more seriously.
I think it's the other way around. Because of Sony's involvment, I'd say investors from probably many large companies were pressed to buy stake in Occulus Rift ASAP to make a dent in the VR market should it become big. Facebook probably had the biggest offer on the table and that's the end of the story.
