It appears that (for the time being) Seaport Pizza is operating on a seasonal basis. I have found the location open in the summer months (and spring break) when the park is at it's busiest, but not over recent winter/holiday periods (when the park is also busy). On my most recent trip, it appeared that Seaport Pizza was testing out a "mobile order system", but I never saw a single customer go in, or out of the building over a 10 minute period.

If you really want a slice a pizza, the near-by Expedition Cafe might be able to help you out. Most of their "Italian" menu is various varieties of pizza.

There are some quiet, covered seating areas on the right-hand side of the main pizza pickup windows.