There are jurisdictions, where Bitcoin is illegal. There is no need to focus on a particular data in the chain, to sue someone. It can be done easier, by accusing someone of "money laundering", or anything like that.

And then, it should be easy to guess, why there are that many nodes, running behind Tor.

For example: https://bitnodes.io/nodes/

Nodes: 24354
Onion: 15595 (64.03%)

It is probably much easier to sue someone, just because of running a node, than to focus on the data being processed. Otherwise, a lot of clearnet sites, like many image hosting sites, would be endlessly sued. But guess what: they are running just fine, and they are not responsible for data, uploaded by their users.

If you upload something to some image hosting site, then there is even no blockchain at all, and everything can be conveniently linked in a format, accepted by browsers. And somehow, these things are not taken down. Guess why.

There is no difference if you want to trace someone running Tor, because of just using Bitcoin, or because of sharing specific data.

Also, there is no need to chase nodes. In practice, a lot of users use SPV nodes, and other kinds of light clients, so they mostly process only their own transactions.

And there are also many "block-explorers-only users", where they just trust some block explorers, like mempool.space, and if something is there, then they believe, that it is always on-chain. And then, it is all about convincing a given website, to display something in a given way, even if it is not really there. Because many users don't care about sharing data in P2P way: they care, if they can link to some explorer, and show everyone, that their JPEGs are displayed there.