In light of recent events I would like to know if a Jew may own and operate a blog or website which is open to comments if it is found that comments can often contain lashon hara, rechilus or motzei shem ra. Is there an obligation to moderate and remove comments that the owner feels violate those issurim?

Would such a site/blog run afowl of injunctions not to perpetuate sin(ners?) such as m'saiyah l'yideh avaira (helping the hand of sin), not placing a stumbling block before a blind person, kol yisroel areivim (all Jews are guarantors one for the other) etc.?