My interpretation is:
Grier sees the core players (Celebrini and Smith, maybe Eklund and Askarov, and perhaps future prospects like Dickinson) as the only players who matter to the future contending Sharks team; everyone else is ultimately expendable and replaceable.
Consequently, Grier has placed a value on every expendable player and does not intend to deviate from that value. If Zetterlund wants too much money, Grier is going to trade him rather than be locked into an above-market deal. This doesn't apply as much to UFAs, but no UFA he has brought in is a core player.
In trading away players, Grier values ammunition, rather than a player. Draft picks are fungible and will appeal to almost anyone. Prospects are almost as good, but their value is less fungible, as teams are going to have opinions about the quality of specific prospects.
Finally, Grier is very confident in his ability to go expend that ammunition to bring in new, replaceable players. Zetterlund wants too much money? We'll go without him for fewer than 20 games and then bring in a new Zetterlund during the offseason.
I do not believe Grier places much stock into the "team chemistry" idea I see brought up a lot here, and in general I agree. Prospects like Celebrini and Smith and Eklund are not going to be ruined because the Sharks are bad, or because they lost a specific teammate for six weeks. Teams like Buffalo don't fail to compete because of "team culture," they fail to compete because they thought players like Thompson, Cozens, and Quinn were future superstars, and dumped Eichel for Tuch and assorted garbage (Krebs, Greenway, Ostlund). I think Grier knows that Celebrini and Smith and Eklund are going to be just fine when he puts $64 million in front of them, and knows they're going to be just fine when they're passing to someone Grier trades that 2nd to in June.
I do think Grier did not get full value for Zetterlund. I also think he knows that, and I don't think he cares. He's going to replace Zetterlund.