The DeFi contracts they made do actually work: you can use them permissionlessly. You don't actually need Uniswap's website to exist to use the contracts and exchange tokens, it's just that it takes some technical ability to do so. Uniswap in fact banned some tokens from their frontend website to avoid scrutiny, but they're still tradable using the contracts. It's possible to cache an old copy of their website and use it to trade, or simply download the website from github and run it locally.
If push came to shove they could decentralize the frontend further but it would be less convenient to use. They simply thought the entire thing was decentralized enough as-is in this supposedly free country, since the blockchain is doing all the heavy lifting, not the website. It's a cat and mouse game the feds will lose. There are Uniswap clones everywhere already. DeFi is coming to bitcoin in a big way very soon. The only thing the feds can do is tank the value of Uniswap's token and financially punish the American devs for having made it out of spite. The actual service is unstoppable. Defi doesn't need a token to work in the first place.
If push came to shove they could decentralize the frontend further but it would be less convenient to use. They simply thought the entire thing was decentralized enough as-is in this supposedly free country, since the blockchain is doing all the heavy lifting, not the website. It's a cat and mouse game the feds will lose. There are Uniswap clones everywhere already. DeFi is coming to bitcoin in a big way very soon. The only thing the feds can do is tank the value of Uniswap's token and financially punish the American devs for having made it out of spite. The actual service is unstoppable. Defi doesn't need a token to work in the first place.