Why is it that self-righteous sanctimonious naturalists like Henry David Thoreau proudly state that they are virgins?

They talk all about being "in touch with nature," "living peacefully in nature," but they vehemently disparage sexual intercourse as sinful, 'dirty,' or somehow being against nature? Sex/procreation is the most natural thing there is, in fact, our entire lives are dedicated towards procreation and producing offspring.

Hypocrites like Thoreau also repel society and community, instead seeking solitary lives. Since when is being solitary a part of nature? Wolves run in packs, human families live in houses, bears live in dens. It seems to be that these kinds of naturalists speak up for nature and ignore the most primal and primitive urges and systems of living.