Wrap Positive Cable w/ Battery Relocation?

Whether it's overkill or valuable protection, I'd listen to him and go ahead and do it. Put it in the "chicken soup" class - what can it hurt?
If nothing else it will give you some peace of mind.

What's your concern?
Expense? Then it's cheap insurance compared to the total cost of building your car or having to replace it in case of an electrical fire.
Weight? Sheathing material can't be that heavy to effect either your mileage or quarter-mile times.

Sounds like a good idea to me and something I will do when my build gets to that stage.
Please post up what he recommends for sheathing material.
Thanks!