However, bicyclists need to get their shit together in terms of pedestrian respect and traffic rules. I can cross a street pretty easily but crossing a busy bike path is a real challenge. I‘m sure we will figure it out in due time.
It also seems that the entire sidewalk is fair game for bicycle parking, which is a disaster for people navigating with a cane, but that can be solved with dedicated bicycle parking.
I would think that at a traffic light, bicycles should act the same as cars, but this just doesn‘t happen at all. I‘m lucky if bicyclists don‘t blast straight through a zebra crossing. It feels especially cruel for traffic lights that are placed between the bike path and street yet require a button press.
So it‘s two things: inconsiderate cyclists and and no common pedestrian crossing system on bike paths (or clarity on rules at existing street crossings).
If bike infrastructure is done well, it should be accessible enough that those disabled people who can ride a bike are able to use it: https://www.theguardian.com/cities/2018/jan/02/cambridge-dis...
Now, you're right that people with some disabilities will not be able to cycle, or will not require a mobility scooter. (Although if you want one and can't afford it, that's also a problem, and I believe a common one here? Our healthcare system...) It's still important to have various accessible modes of transportation. Trains can be a good option here, though it's important that they have level boarding for wheelchair users and that all stations are likewise accessible. (Philly's unfortunately are not. The City Hall station reconstruction is long overdue.)
And some people may always still need a car due to their disability! In the Netherlands, they have something called the Canta, which is a microcar specifically for people with disabilities that's small enough to operate on bike paths and can be parked on the sidewalk: https://en.m.wikipedia.org/wiki/Canta_(vehicle)
And yes, some may need a full-sized vehicle as well; it's worth replacing some parking spaces with disabled parking spaces to accommodate that case.
My point, though, is that our car-centric city designs in the US don't accommodate everyone either! We often consider it to be the default out of inertia, but it's important to remember that not everyone can drive a car, and in a car-dependent area that's a recipe for social isolation. Our cities should be designed such that everyone is able to get around quickly and safely.