It could just be for the PHL route. It's switching to LAA soon, so if they want to have Dutch speakers on board, they'll have to hire new ones, as the current ones are LUS and won't be able to crew the LAA 757. (For now, anyway.)
The job ad only mentions LAA hubs, so it's definitely for the LAA side, in any case.
With that being said, I would love another route from AMS, though.