Reidentification via writing style is definitely possible, and I doubt the vendor will modify things in a way sufficient to handle that.
But I think this is a place where we should apply bounded distrust: there are lots of places where we should distrust Google, but reidentifying people in an explicitly deidentified dataset isn't one of them.
Based on their trackrecord, That's definitely a concern. I don't really understand on which basis you conclude 'isn't one of them' . 'Don't be evil' ? :-P
The re-identification is done by ML, at which point it's basically undetectable. If you give all this day to, say, and LLM, and the LLM also has your blog, the identification is embedded in the weights.
I can ask "Tell me about Person A's experience with airlines" and it will tell me. Or I can ask more generally, "knowing your knowledge, derive a no-fly list", and then it's likely Person A will be on it.