Some version of the jet-wash explanation seems to have been made public in 1988. Here's a contemporary New York Times summary of some February 1988 Pravda articles: http://www.nytimes.com/1988/02/07/us/soviet-lifting-veil-on-...

That report, which Leonov was a co-author of, identified the other plane as a MiG-21, not a Su-15, but otherwise seems pretty similar to this account.

I'm not sure why RT here is reporting Leonov's updated version of events as if it were just now made public, either. He published this version (involving the low-flying Su-15 passing within 10-20 meters) at least as early as 2004, since it appears in English in his co-written book Two Sides of the Moon (http://www.amazon.com/gp/product/0312308663/ref=as_li_ss_tl?... ; Chapter 8).