A really excellent explanation, thank you.
I had retired at the time of that collision but when I did my TCAS training ( B757/767) we certainly would have gone for an RA until the situation was fully resolved.
At the time of the accident, discussion with former colleagues, after reading the report, we gained the impression that might not have been the case in Russia, which , perhaps is why the Russian pilot did what he did.
Again thank you for such a detailed and authorative explanation.