Earlier quoted context omitted.
They're saying they won't train generative models that will literally regurgitate your text, my guess is classifiers are fair game in their interpretation
The OP privacy policy explicitly states that autocompletion algorithms are part of the scope. "Our algorithm that picks from potential suggestions is trained globally on previously suggested and accepted completions." And this can leak: for instance, typing "a good business partner for foobars is" might not send that text upstream per se, but would be consulting a local model whose training data would have contained…
This is explained literally in the next sentence after the one you quoted: "We protect data privacy by using rules to score the similarity between the typed text and suggestion in various ways, including only using the numerical scores and counts of past interactions in the algorithm."
If all the global model sees is {similarity: 0.93, past_interactions: 6, recommendation_accepted: true} then there is no way to leak tokens, because not only are the tokens not part of the output, they're not even part of the input. But such a simple model could still be very useful for sorting the best autocomplete result to the top.