He did literally say that a character who didn’t have anything to spend a huge pile of gold on is a “pure player avatar.” Right here:
Okay, but this is what you quoted.
"Okay, let's consider the adventure path hook "Save the world from being dominated by Tiamat manifest". There is a fairly obvious question about this hook - why does the
character care enough to go on the adventure rather than stay home, disappointing his wants-to-play-D&D player? Because pretty much any answer to why a character cares about that translates into a use for gold. The character might be an altruist who cares about suffering (and so would spend gold on relieving suffering), or a hedonist who thinks that a Tiamat-dominated world would be less fun for him (and so would spend gold on hedonism), or whatever, but it's incredibly difficult to come up with an actual character that has no use for gold, but enough motive to actually adventure."
Nothing there says, "I find the notion that a character who would rather the world they live in not be dominated by an evil dragon-god must necessarily be a hedonist, and at that, a hedonist who is driven to indulge in hedonism
vis a vis spending money pretty absurd."
What the quote above and the smaller quote you just provided to me are saying is that a well rounded character will have more motivations than just, "Must stop Tiamat!" He wasn't saying that a character who didn't want a world dominated by Tiamat must be a hedonist.
I also don't really understand the last part of your quote there. Of course a hedonist will use money to engage in hedonism. Money is a primary way to be able to engage in new experiences. Want to experience a fey originated drug with magically chaotic and enjoyable results? It will probably cost money. Want to experience a hunt for a rare white stag? Paying a local hunter to help guide you is a great way. Money gets experiences done.