It remains a despicable act of terrorism by an entire country, and don't try to shift the blame onto the crew by saying they should have known.
May I ask your definition of terrorism ?
So if an aircraft gets hijacked, flown to a different destination and the hijackers surrender taking only one hostage with them - that's not terrorism?
Normal SOP's for bomb threat is LAND AS SOON POSSIBLE, so the question is why did the crew not follow this SOP? Why would you risk flying double the time you needed into a country that is run by a dictator, and the issue was only if going to Vilnius according to Belarus ATC transcript.
This crew were told that if they flew to Vilnius that their aircraft would explode - what did you expect them to do?