Can I cook beans without salt?
Yes.  In fact, many, many people believe (falsely) that adding salt before or during cooking will keep beans hard (a myth addressed in your first link), and most of these people have been cooking perfectly good beans for many years without adding salt until the beans were fully cooked.

The cooking time may vary slightly.  In some circumstances, the texture of the beans and/or their skins may soften at somewhat different rates than with salt.  But the beans will still cook fine.

(One note: some chefs have claimed that cooking beans without salt causes people to add even more salt afterward to create a flavor that tastes "properly salted."  Beans are generally enhanced by adding flavoring components early enough in cooking for the flavors to penetrate.  But you can always add salt afterward too; the resulting flavor distribution will just be different.)