point8six;
that the pilot had already commenced rotation when the observation from ATC was received?
Yes. I'd have to take a look at the final report to see if #1 was exhibiting problems at rotation - it certainly did soon after. As you say, and as is the point of the post was, at/near/past V1 "correct" decisions are more closely determined by circumstances and outcomes than the books.
Clearly, practising/training for an RTO after V1 may be something that many may personally advocate for reasons already known, some stated in the thread, but the fact is, successful outcomes are rare, and, there is no basis in certification or numbers in the AOM for such a decision - I think that's the only point.
Until the latter is made known, it is all speculation.
Agree, of course.