I think that sentence meant "the difficulty of reading at a young age makes them less interested in reading when they are older"

Hmm, oh yeah, I think you're right.

(Personally I was reading by the time I was four without my parents doing anything more than reading to me on a regular basis, and maybe setting a good model by reading a lot themselves.)

Yeah, you're correct. I'd edit it to be a bit clearer, but it's too late.