I’d say any automated/integrated effort to direct users of federated instances to the threads site to view content should count as a strike. (Such as needing to go directly to the threads site to view an image that could be easily posted anyway.)
So should any automated/integrated effort to encourage users to make their own threads account. (Such as needing an account to visit this link or view this image.)
Any attempt to coerce non threads users to sign any sort of agreement or TOS with threads.
As well as any data collection on non threads users. Merely interacting with a federated threads account should not entitle meta to any data collection of that user.