he left it safer than when he started and in my opinion, no less safe than it had been for the est. 30 years previous to the bathroom work.
in his situation with time limitations, I would have done the same if it was a member of my family.
the only thing i may well have done would be to do an earth loop test using the case of the mirror as earth to check for a good earth connection to it as the terminals were not accessible. for all we know, he may have done that but not videoed it.
edit,
I don't recall him stating that it was dangerous (I could be wrong) he did point out it was a poor quality job and there were many things wrong with it from a standards point of view. most of the issues were correctly rectified in my opinion. the only thing left is for rcd protection at a later date.