Few of us have access to the unvarnished truth, so I can't confirm its veracity, but here's a partial explanation jolihokistix:
Filipov’s suicide was actually in vain. He came down inside an area controlled by Jaysh An Nasr, and would therefore have been captured by JAN and not by jihadists.
The Russian pilot would almost certainly have been exchanged via Turkey. The same happened with three different Syrian pilots in 2017.
Reported via Warisboring.