The con was only partly about who got what artifact. The most important element was getting Nicodemus to break his contract with Mab. Now if Nicodemus had left no survivors, it wouldn't have mattered, but he did and that meant everything. Now no one will trust Nic or deal with him. His strongest potential allies; his ex-wife and Lasciel are one; not in any mood to be helpful; and two, currently trapped in a coin under several tons of rubble inside Hades vault. Add to that, Nicodemus got his ass handed to him; and word of that must have been spread far and wide by now; so there's a loss of face; plus, Nic lost (murdered) his closest and most reliable ally, his daughter Deirdre.
The condition of one or both of Nic's potential allies may change in the long-run. Plus, Nic did get the grail. However, I think the one factor everyone seems to have forgotten is that Nicodemus still has one of the coins in his possession. My guess is that coin isn't a simple thug denarian like Ursiel. I think Nicodemus needs someone capable of being a truly useful ally to carry that coin. The Genoskwa was just a thug so a thug's coin was perfect for it to carry. I don't think Nicodemus wanted someone as capable as Goodman Grey to be just another thug on his payroll. Nicodemus seems to be quite aware that the endgame is coming soon and he needs to marshal all his strength and assets to accomplish his goals. Part of the beauty of Mab, Kringle and Marcone's plan, was it made it exponentially more difficult for Nicodemus to find someone the caliber of a Goodman Grey, who would be willing to even do a sit down with him and eventually take up the coin formerly held by his daughter.
