The texture table implies that it does not

This is just a typo in the spec right? The feature itself says
25.13. "bgra8unorm-storage"
Allows the STORAGE_BINDING usage on textures with format "bgra8unorm".
This feature adds no optional API surfaces.
Which I assumes provides both read and write. There are tests that it's readable and they're passing when bgra8unorm-storage is enabled.