Karl, I’ve never heard anything different. AFAIK when the rule book says Mongolia will only become pro-Axis if attacked directly by USSR, that’s what it means.
If any other Ally attacks a Mongolian territory, the rest of the Mongolian territories will not go pro-Axis. Because they were friendly to Russia? I don’t know, but that’s how the rule book reads, so unless Krieghund comes on here and says different, than you are correct. If UK attacks Mongolia, the rest of the Mongolian territories will stand pat, and all other strict neutrals in the world will go pro-Axis if that hasn’t happened already.