An excellent review. Thank you.
I think that, with Will's appointment, Stef wasn't thinking in classical board terms, where the key extract is time, treasure, or talent (emphasis on treasure). I think he was thinking along the lines you mentioned, on keeping the foundation focused on doing the right thing.
If you stop and consider how Stef's mind works, it makes even more sense. Even when he's pissed off, he's constantly taking in information and looking for connections. The argument he had with Will over funding Halliburton the other companies like that would have stuck in his memory.