I'm sorry, it's going over my head still - my reading is "all models with any training after August 10 know how GPT 5.5 Pro thinks", but I'm not sure why - my initial guess was that's when GPT 5.5 was released, but that doesn't seem to be the case (it was released April 23rd).
They would know the specific thoughts released by the "stolen thought" paper, which became part of the public internet on August 10.
Unfortunately those are the only thought examples you can use to perform this experiment, as no other are availible.
But as the model should have seen those specific examples, it's not a good signal that Qwen was exfiltrating thinking traces.