Nevertheless:
06/25 14:37 RUSSIAN LAW ENFORCEMENT AUTHORITIES MAY DETAIN SNOWDEN TO ESTABLISH ALL CIRCUMSTANCES, INCLUDING PASSPORT DETAILS - SOURCE
06/25 14:37 RUSSIAN LAW ENFORCEMENT AUTHORITIES MAY DETAIN SNOWDEN TO ESTABLISH ALL CIRCUMSTANCES, INCLUDING PASSPORT DETAILS - SOURCE
This is not the case in most any other airport on the globe, where you usually remain in the transit zone if you're travelling to a third country.
That said: I agree with you that the Russian statement is likely a cop out. If they want to arrest you they wouldn't give a shit if you're in the transit zone or not. That probably goes for every other country too.
And yes just as you said, IMHO transit zone is not a safety zone from the hosting government, it is more just a convenience thing for the travellers.