I suppose someone might argue that it's a "sidewalk" for the pat bay which would make it "bicycle=no" but that seems like a stretch. 

 I feel like there should be some way of marking these paths that don't prohibit, or even in some cases designate that cyclists are supposed to use them, but its a bad idea due to the nature of the actual built infrastructure.

bicycle=discouraged requires specific signage so it doesn't work.

Maybe measure the width from an air photo and tag that to provide a bit more context I think it was maybe 1.5 m or so?