The first couple of books in the series were published in 2014. I'll have to find out if there has been any of the kind of push back you describe. The author finds it difficult working with school system bureaucracies, but that's because they're bureaucracies. Finding like minded teachers has been more effective. I wonder if the teachers are getting any this flack.

The objective is to help parents reclaim the education of their children. I turns out parents are the ones learning about classics that have been ignored by government monopoly schools.