There is also a section of some aircraft designated as "priority" seating where they say they might move if you elderly or disabled passengers need that space. However, that's clearly indicated on the website when you select the seat, so I don't see an issue with that.

Frankly, I prefer to choose those seats because as a GO, if the flight is full and they need my specific priority seat for some other pax, I'm more likely to get bumped up to J.