Take a look at some photos of Tupper Lake station as it currently exists:
https://www.waymarking.com/waymarks/wm7 ... 5_Depot_NY
The ground between the tracks and the station is a combination of gravel, dirt, not exactly level, and has some embedded concrete, aka tripping hazards. Yes, they ran a couple of inaugural trains up there last year, but it is simply not in suitable condition to function as a terminal station on a railroad. I imagine the railroad will try to work with tour bus companies, especially in the fall, and those tours usually carry a lot of older folks who don't mix well with muddy, uneven ground. There is also no public parking to speak of there.
This image from the Empire State Passenger Association (need to scroll down a bit) shows the proposed work, which includes the platforms, siding tracks, wye and a service facility.
https://www.esparail.org/news/adirondac ... on-begins/
As for platforms at Sabattis and Beaver River, I'm more inclined to agree that they might be superfluous. But they are still in the plans the last I heard, and that work will affect the ability to run trains through those areas.