Deleted my comment.
After looking into it more; there is access inside, but it's typically secured with a pressure differential and several locks.
They'd only really access it if absolutely required; for example to fight a fire in the cargo hold.
Bathroom would have been a good solution. Or just move her to a back seat and move the living passengers away. Bizarre they forced a couple to sit beside her.
https://archive.ph/20250225180133/https://www.ft.com/content/2dfa3c11-64a7-49f6-83df-939b8d1cfb8e