Ex-religious people, who had previously conflated atheism and other religions, might be less prone to being binarians after becoming atheists.

Sample size of one, but I also have to remind myself as MarkusRamikin does. I was openly religious up until about 18, and was only someone I'd consider a serious doubter at 14, with relapses at 16 and 18. Prior to 14 and between the lapses, religiously pretty strong.