If I was training then I would train the student in tactics to the best of my ability. If not that then I wouldn’t train.
Yup, absolutely. When you work with someone in person, you owe them your very best.
That has nothing to do with whether you "owe" it to everyone in the world, including some nameless and faceless internet name, to tell them everything you know.
Some techniques and some information are best reserved for in person.