Earlier quoted context omitted.
Most gear should have a feature called RA Guard which will block this put of the box and you should run it regardless of this vuln because your clients shouldn't be advertising as routers on your network.
Any idea if RA Guard will block unicast RAs? -- it wouldn't need to for the ordinary purpose of blocking misconfigured devices.
I can't speak for every implementation in the world but at least most block both as it actually takes more work to create a filter that only blocks multicast RAs. The filter to block all is an automatic ACL saying "ICMP Type 136, direction ingress, action drop" and a multicast only version would take additional checks to do less.