Was Ross Ulbricht ever explicitly pro-Bitcoin? His Wikipedia page described his libertarian bend on economic theory and his belief of a commerce platform with complete anonymity. Bitcoin isn't necessary anonymous, every transaction is recorded and of public record. Life sentence seems harsh, though the US likes to make examples out of anyone involved in drug related crimes so there isn't a chance in hell he's ever going to get out.
Bitcoin's blockchain is public, but if you do proper coin control and use coinjoins, you can increase your privacy by a lot.
As for him being pro-bitcoin, you can check out his speech on Bitcoin Miami 2021 from months ago:
https://www.youtube.com/watch?v=3V_SkLxgQjQAnyway, back to the topic, why does this have to be an NFT? Why not just sell his artworks physically? If the artworks are delivered physically, what's the point of this NFT? If not, where are guarantees that they ever will?
Obviously I don't know his answer, but it's just either that he "likes" NFTs(or at least think it's interesting), or the most likely reason that it's pretty easy to pool a lot of money on NFTs if you have a big name.