The action is usable. Still, it should not be possible to stall the game this way.
Problems can happen when there is an action that has no costs or effects and can be repeated infinitely many times (like making
Uruk Fighter fierce when he is already fierce). Then you can use it to steal the time (which sometimes may be important, I had one league game when since site 2 I knew there is no way I can win other than my opponent running out of time)/ I think the game should recognize an action that has neither costs nor effects and if a player does two such actions in a row (with opponent passing) a warning should be displayed that next such action will count as pass.