Okay thanks that's good to know, we will do it his way in future games as well.
I should explain my confusion, it was with how they worded it in the rule book. They write ..."He may expend 1 point of might per turn without reducing his might store"
So i thought of two things immediatly......
1) expend means to spend, to use up, or consume. So i figured he can't consume 0 points. It's impossible
2) to have a "might store" he must have at least 1 might in store
But i understand these things are not always straight forward, and it was probably in an FAQ by GW somewhere. So i accept the ruling. Thanks for the reply