He was just picking who was their biggest partner at the time and throwing shade at their biggest competitor. NVidia was also throwing a lot of shade at PlayStation at the time.God damn, I thought that guy knew a thing or two about making games.
Valve has a long history of hating on Sony and they probably still very indisposed with them seen as how they don't reciprocate anything (PlayStation supports Steam but Valve doesn't support PlayStation at all not even on the VR front where they try to work together with everyone).
It's smart from Valve and NVidia to acknowledge who their direct competitor is, the same can't be said about Sony (that sees both as partners).