It’s a great quesiton, and I’d love to know the answer too!
I’m thinking multiple models would have to be used.
One is pose detection which captures a sequence of poses over time.
One is a sequence model, trained on sequences of poses to classify them as ‘good’ or ‘bad’ or some other label.
At runtime you then capture the sequence using the posenet, pull out the relevant parts of the skeleton, and feed that into the sequence model to get a classification.