So this seems to be way more of a problem with your 1 player who seems to be incapable of handling 1 extra action than a problem with the design of the animal companion. It's like saying, Haste is horrible because 1 guy at my table doesn't know what to do with his extra action. It should be removed.
Make the guy figure things out faster. If your group is experienced enough and trying to discuss moves during the heat of combat or moments that are time sensitive, put a timer on them and if time runs out any actions not done yet are wasted.
