i dont want to get overly hypothetical but its common sense that the hvr will most likely be able to cover the objective, which forces you to deal with them before the actual mission - something i find to happen fairly often is killing the hvr and advancing on the objective only to have the same hvr respawn behind you
aside from that, saying "well just take your team and kill the hvr" only shows how much the hvr can affect a match, to the point where (similar to carspawners) they almost become an extra objective on their own