Ya, infrastructure is definitely gonna cause patch to come later.

This is my guess as to what they need to do.

"work on Infrastructure"

"Implement patch"

"Test Island Exploration with 9 groups entering at different times"

"If there is an issue tweak with Infrastructure to figure out issue"

"Implement Patch again"

"Try Exploration again"

"Rinse and repeat til they are certain there are no issues"

The reason I'm assuming Island exploration is because this content is one that treats instances differently from all other content that has been released. All content so far has had instances with a global timer, the moment of first entry and the exit time never change. Enter dungeon halfway, then you have the same amount of time left as the first person who entered. With Island exploration however you have 9 groups, 3 groups could share the same time but it's assumed that at most there will be 9 groups on 9 separate timers from entry meaning that if they want to make sure it's done right they have to be certain that they don't run into an issue where groups that enter after the first don't have the same timer as those who enter later on.

You wouldn't want to be group 5 entering 40 minutes since the instance opened and being given only 50 minutes to explore, that would suck and that's the part they need to adjust for the servers to handle the variables of different people having different timers on their instance duration.

The other thing to handle is how the dungeons refresh, these open instance will most likely have triggers to reveal bosses but see if three groups are in alrdy they might of beat a boss already and they have to make sure it's setup where the triggers for these bosses reappear right away/enemies respawn but since this does go across multiple servers and it's done through an instance, they are most likely deciding whether these instances will be open indefinitely or if they close after time and new ones are created as time progresses.