And the reason it's impossible to say is that Snead never gave any indication he wasn't all in on the GRob pick.
We all know Fisher hired Snead to effectively do his bidding, but my view on Snead's culpability is very simple. He is culpable for all of it since he both accepted the gig, and thereby the responsibility, and he promoted everything they were doing with full force and vigor.
At the end of the day you end up arguing whether Snead is a bad GM or an unadulterated Yes Man, which effectively becomes a distinction without a difference.