Would it be a " retaliatory response", or just an effort by a law maker to prempt future attacks?
Not knowing anything about this particular politician its hard to say one way or the other. His action could even be a combination of both retaliation and premption.
exactly what rights the accused have to comfront the accuser...if it were to go to court how would the injuried confront the offending party
That's part of the problem. The victim could not seek damages for libel without naming an offender that would be subject to prosecution. To complicate the case further would be the matter of establishing jurisdiction since the alleged offense is talking place on a web site.
Further, the courts have ruled that there is a much higher standard for public figures seeking redress of grievances through litigation since negative statements about them are generally protected by the First Amendment's freedom of speech clause. That's why political activists and campaigns can engage in smear tactics and misinformation against an opponent. The courts consider all this as political discourse.