Playing clock is used in all the sports and games. (i dont talk about real tome but killing turn).
For me, it is a fair tactic as long as it is risky.
Staying one more turn and you can loose the ball. If the opponent can 't reach you, so he made a bad defence.
Some Teams have to kill turns to be sure to get a draw or a victory (against high speed teams) and i feel it fair.
In the same time, with speedy teams, loosing a turn is usefull in the same way (letting 2 turns for dwarves to score is not bad

So do you really think it is unfair?
IMHO, it is a fair tactic (i wont pay for my opponent mistakes).