Also, the actual quote was "This scam product has been discussed here before. Stay away. It's a marketing ploy." Which I guess may be legally actionable, but given their behavior seems like it's quite likely true.
If MMM gets a lawyer he's going to end up defending the content of the post, not his right to operate his site independently.
Notice and take down is a process operated by online hosts in response to court orders or allegations that content is illegal. Content is removed by the host following notice. Notice and take down is widely operated in relation to copyright infringement, as well as for libel and other illegal content. In US and European Union law, notice and takedown is mandated as part of limited liability, or safe harbour, provisions for online hosts (see the Digital Millennium Copyright Act 1998 and the Electronic Commerce Directive 2000). As a condition for limited liability online hosts must expeditiously remove or disable access to content they host when they are notified of the alleged illegality.[1]