Transit hubs do meet both the explore and social criteria, as it may be a good place to meet up with others, and it encourages you to get out and explore your community. Directional signs do not meet criteria, as they are pretty indistinct in a place like a transit hub; there is even clarification on these (this is under trail markers, but also applies here):
However, this station already has a Wayspot, and being the rejection reason is Wayspot criteria, it appears to have been rejected by ML, the AI system, for being a duplicate or not meeting criteria:
I’m thinking this is not showing up in the game you are playing, and this could be due to the other Wayspots in the area.
Each game uses the Niantic Spatial map to determine game play locations, with the exception being Power Spots, and each uses different density/inclusion rules. PoGo uses S2 cells, while Ingress uses a 20 meter rule. More on S2 cells can be found here:
https://pokemongohub.net/post/featured/comprehensive-guide-s2-cells-pokemon-go/