A message to the West perhaps?
> The western fascination with them is a kind of exoticism.
But the West is important to them. They know the fascination and they know the West is watching so they just showed everyone they can be ruthless.
It could play on the angle that Westerners should be careful about supporting too much someone like that as their popularity could end up killing them. For example, say Harvard wanted to invite Verzilov to give a talk. Now they might think twice - it would be nice to have him, but would they be painting a target on his back because of it? So it has kind of a secondary chilling effect.
Another reason:
> Verzilov had been working on an investigative story about the deaths of the three Russian journalists, Alexander Rastorguev, Orkhan Dzhemal, and Kirill Radchenko.
It wasn't that he was particularly dangerous because of his political stance but because he started to dig into other journalists' suspicious deaths. So he might have been a no-name but got close enough to uncover things.
One more reason:
Eliminate the troublemakers early. Don't wait till they become popular. Have someone monitor the media and detect who is becoming "dangerous" and eliminate them before they have a huge following.