Anthopic choosing to delay their models' invevitable distillation by competitors is their prerogative.
That they choose to implement it by fingerprinting my access patterns without first disclosing is where they shit the bed. It isn't "sneaky" it's straight up sneaky (and dishonest and unscrupulous while we're at it). That this particular instance is harmless doesn't give me much comfort. Who's to say they aren't harvesting PII?
That their actions make sense for their business isn't any reason for people to accept their deceitful, customer-hostile decisions.
Would a filter like this make it seem less likely that they're harvesting PII? Why would they need this if they were tracking all user queries with a finer-toothed comb?
If by a "finer-toothed comb" you mean telemetry then I don't quite see it as comparable to this situation.
Telemetry is disclosed in privacy policies, it can usually be opted out of and if not that, then it can be blocked by a firewall. Steganographically fingerprinting customer's network routing when they consented to your tool reading a txt file is a different problem. Anthropic has demonstrated capability and willingness to embed arbitrary obfuscated data in their comms streams and that's a dangerous precedent to set.