I dont think its wrong to allow a child a two mile walk to school, I had a just under the three mile walk back in the 70's ( hence no free bus pass ) and then aged 13, I did a three mile paper round before hand
Sure I got wet, but back in those days - no one thought of saying you need to change blah blah , life wasnt as cosy
What I would say was "horrible" ( your words ) is making your problem his.
Put him on the bus, you dont need to get on it
Yeah I get it that school buses - ie buses full of kids going to the same school - are loud , busy and can be bullying, but he has to grow up himself and face these challenges himself
Wrapping him in cotton wool because of your fears and anxieties , is really going to make his life difficult, Im so sure you dont want that