Can I upgrade somebody else to gold edition?

Me and my friend both play Civ V, but he doesn't have the gold edition. He just kind of ignores me when I tell him to upgrade it (don't take this the wrong way, he's a really cool friend), and since his birthday is coming up soon, I was wondering if I could upgrade it for him with my own money. Whenever I go to the page on steam, however, it only lets me buy it for someone else as a gift.

So is there any way I can upgrade for him? Thanks in advance.