Thank you for starting this thread OP its fascinating 
It's really opened my mind to another way in life. I've often thought school is for some children something they spend the rest of their lives trying to get over rather than the postive learning experience it should be.
There is one person I know who would have been absolutely suited to HE and could have avoided years of bullying and unhappiness.
I think alternative paths should be considered rather than the belief there is only one way to success. Its makes me chuckle really reading all these rigid views about the school system, Uni and future prosperity. In my circle I know two highly successful individuals who came out with no qualifications from school and are now high net worth individuals with global companies. On the flip side I know graduates who can't get anything more than a minimum wage job because they have no work experience and there is so much competition. I'm not saying one way is right and the other wrong, just as an individual its is better to follow your own path to effective learning and mental wellbeing. What society thinks is largely irrelevant as it doesn't actually experience what the individual will nor will it pick up the pieces of an unhappy childhood.
Of course there should be safeguarding measures in place to protect vulnerable individuals but this can be to support HE. How many children are not safeguarded from bullying and physical violenece in schools? Probably a higher percentage I would guess. Pastoral care and safeguarding should be more effective on both sides, neither have got it right in my opinion.
Both my children will go to school. It currently suits my son as he is gifted in maths and is stretched at school but if it doesn't in the future or my daughter has issues I would considere HE.
Good luck to you OP, I for one think you are admirable in adapting to your sons individual needs and giving him the tools he needs for success in life.