I agree. I can kinda maybe see using your points at time of transfer, if that's a policy I could probably live with that; but paying for the whole booking including cash ? That's too far.
This is the only time I've encountered it, but this was my first time using a points currency. I previously used Discover's agency but because that's cashback it was different. Never had just a regular TA with a cash booking ask, they follow whatever the cruise policy is. Worst you might have a slightly earlier PIF, like a week or so, to account for any unexpected payment delays. It sounded like it wasn't this way before with Chase either, so that's why I'm wondering if it's a change around how Chase changed up their travel portal.