“A bitcoin transaction transfers taproot assets, and the sender publishes proofs to the asset universe to finalize the transaction.” This is only accurate if we are talking about a pocket universe.

The data structure of Taproot Assets involves a few layers of Merkle trees. When you own a Taproot Asset outright you hold all the keys in that set of trees. But in the case of a pocket universe, the asset holder holds the keys at the bottom of that set of trees, but the pocket universe operator holds the keys at the top of that set of Merkle trees. ...it’s sort of a hybrid custodial situation. In this setup it is fair to say that “universe to finalize the transaction.”

However, if you hold an asset outside of a pocket universe, you hold all the keys and you do not need to wait on any universe to finalize the transaction.

Here the naming is a bit confusing. A “pocket universe” is really a very different thing from a general “universe”. A general universe is simply a data store. It is a database where onchain transfer proofs are stored. If you are running a Taproot Assets node, you are running your own universe.

It is accurate to say that a stablecoin issuer could decline to redeem coins that have proofs associated with addresses that they don’t like. That is accurate.