Can you explain to me what you mean by "user generated content" and point out the section of the bill that pertains to that.
IANAL, but this seems like the most terrible section 102.c.2.A.i
IN GENERAL- A service provider shall take technically feasible and reasonable measures designed to prevent access by its subscribers located within the United States to the foreign infringing site (or portion thereof) that is subject to the order, including measures designed to prevent the domain name of the foreign infringing site (or portion thereof) from resolving to that domain name's Internet Protocol address. Such actions shall be taken as expeditiously as possible, but in any case within 5 days after being served with a copy of the order, or within such time as the court may order.
From what I've ready, these kinds of protections already exist, however what this does, is allow a claimant to blow past all the niceties of court and get the "possibly" infringing site down as fast as possible, using the DNS as fodder in their personal war. The court proceedings would essentially occur after the site was already removed from DNS.