As an experienced professional public librarian, I am an advocate for freedom of information. However, not every book is appropriate for a public institution, nor is every book appropriate for a child. There are lots of books but only a finite number of them can be purchased. Decision makers should incorporate the input of their constituents to develop policies & buying practices that reflect the shared beliefs of as many members of the community as possible. 

Public Schools are the only affordable option for many children of both progressive and conservative views/upbringings. Public schools should respect both viewpoints and focus on materials that are acceptable (if not ideal) to as many of their constituents as possible. Schools are a place to bring the community together, not a place to debate our controversies, there are other forums for that.

Public schools are not vehicles for advocacy of controversial issues. Items that are sexually explicit or advocate specific beliefs about sexuality or religion alienate and offend individuals of many cultures and creeds. There are plenty of resources that teach the curriculum without pushing a controversial agenda either conservative or progressive and are the most inclusive and fiscally responsible choices for diverse communities.

Public schools are tasked with teaching reading, math, science, etc. Private organizations exist to teach and advocate for controversial issues such as religion, sexuality, etc. Parents wishing to expose or indoctrinate their children in specific sexual lifestyles should join or start an advocacy group or religion dedicated to that purpose. This applies equally to those with conservative and progressive views.

Parents who insist on indoctrinating their children with specific beliefs at school should join or start a private school which includes those beliefs as part of its mission and core values. Many conservative/religious groups have done this successfully and advocates of progressive beliefs about sexual exposure, the LGTBQ+ advocacy, or other similar causes can and should do this as well.