It's a charge. By definition, that means charging. If I'm already in your face, I can't charge very well- having some distance to build up momentum is important- and the same goes for a bloodthirster.
When I say hit-and-run tactics, I mean 'Fly up, charge down and no dodges thanks.' That is how that ability works, right? Kind of like the Khornate Daemon Weapon Rampage ability?