With a hernia like yours, they don't need to know how much you're refluxing to determine whether or not surgery is required. It's a critical situation and there is no doubt. Therefore, the PH monitoring is a moot point.
The manometry is another issue. Since they're likely doing a Nissen, it seems like they'd want to know your swallowing abilities. However, they may be planning a partial or loose wrap anyway, in which case that wouldn't matter either. The manometry determines whether or not your swallowing reflex is organized and strong enough to get food through a full wrap, which is tighter.
My guess is that's the reason, but you could ask. It makes sense to me!
Good luck with your surgery! We'll be waiting to welcome you to the Wrapped Club if you get one!
Nissen Fundoplication 2/09
"Whatever you fight, you strengthen, and what you resist, persists.”
“Worry pretends to be necessary but serves no useful purpose”
“Accept - then act. Whatever the present moment contains, accept it as if you had chosen it. Always work with it, not against it.”