There was no mind reading in 1984, this argument just doesn’t make any sense. As was pointed out above, the French pro-Palestine activists who were jailed didn’t communicate anti-Semitism directly. By simple being anti-Israel it was assumed that they are antisemites and this criminals. Technically this was done by saying their T-shirts were anti-Semitic, but they weren’t in any absolute sense. It all came down to what their thinking was assumed to be.

Comparing this to libel/slander is just absurd. It’s not a slightly different category, it’s such a massive difference that Europe has essentially outlawed aspects of political speech, which is the most important aspect of freedom of speech to begin with.