First, the quotes I sourced weren't finite or temporary statements. They were absolute. /sithBut where does it say that it will be actually be stuck in that timeline for an extended period of time?
Second, the fact that they've spent a billion dollars on a land with two attractions that have characters and situations set firmly in that timeline.
Primary examples being the fact that Rey, Finn, Poe and Kylo are alive and well within the Resistance in the ROTR attraction and the fact that the battle between the Resistance and First Order is on going. The Sequel Trilogy is likely going to conclude with at least one of those characters or circumstances coming to an end. They're not going to overhaul the entire land 7 months after it debuts because the films have passed its point in continuity. The same way it's a specific place in space it is also a specific place in time.