I have always thought the same, time out is to remove said child from what is going on. A time to change the focus for everybody involved.
We have the nanny 911 book, and for lots of stuff its good. But I doubt she would agree to an hour in time out without professsional consultation
I know 5 and 6 year olds can get feisty and unruly but I think your partner really needs to understand time out better before using it.
Its great that he wants to use it, and that hes trying to stick to his guns

Perhaps later tonight you can have a chat with him about your limits as a parent. mention how you felt with your LO in time out for an hour and him not letting you intervene ( that would have been so hard) And talk to him about what he feels is right and wrong to do.
Perhaps some extra research on the nanny 911 website, you can use to help him adjust and be more gentle in his style.

Good luck. This is always a sensitive issue