>he laments that most philosophers think of the sub-discipline of ‘philosophy of education’ as an academic slum occupied by intellectual mediocrities who produce dull and unsophisticated work.

I mean, the problem is, this is right. Most philosophy of education being produced is not worth reading. It tends not to attract the best and brightest... which is a self-perpetuating pattern.

I think the point you make here is fine, and it's strange that you're being downvoted. r/philosophy is not a very philosophically sophisticated audience.