Because there is a difference. My understanding [with the idea...

Because there is a difference. My understanding [with the idea SBU/US/anti-Russians were involved] is they were trying to flee to 'safety'. Belarus would surely be not much safer than staying in Russia in such a scenario.
To be clear I don't completely buy anything yet. I tend toward the Russian version so far though, will see what additional info comes out in the near future.