Timber Deck on Concrete Pool

I agree with your pool builder. The concrete is over 11 inches thick, and your masonry bolts are going in only 2 inches. As long as you can avoid any rebar while drilling, I think you'll be fine. Tom

Personally I would hesitate to put any wood next to the pool. Especially if the wood would drain into the pool. Wood, chlorine, water, sun, just a bad combination as far as I am concerned.

I think structurally it would be sound. But if you are talking about a wood ledger it will be a water trap and cause a dry rot situation. I think you would have to design a air gap between the gunite and wood for air flow. You could attach so kind of flashing to divert water over you ledger. You could also use a composite material for a ledger.