Let people do whatever they want. Let them buy or collect whatever they like. Free market.. freedom
The whole point is that the protocol is permissionless.
If someone wants to pay 2000 for a 2 usd sats, I am willing to sell because they are all the same to me. I need nobody permission to sell, and the buyer also do not have to ask any permission to pay whatever him wants.
Tainted coins are already real, whether you like it or not. It is up to you to find ways to make your coins clean again before sending to centralized parties which will analyze them.