You asked:

I don't know, but I can tell you that the kind of online
harrassing some people in rpca and rph+b (which may be what
brought on this attack) is indeed against the law. It is
called "stalking." Each and every one of you who
participates in the campaigns to terminate the Internet Service
Provider accounts of those you do not like by compaining to their
ISPs leave a trail: your IP number is in your complaint. Those
of you who do this over and over again had better think about it.
There are those with the means and the values to subpoena such
records in order to find out who is doing the harassing.

Stalking is a felony in some states (Minnesota, Maryland, Oregon,
Nevada, and North Carolina and others.) and a misdemeanor in others.
Both can bring jail time.

You cannot legally interfere with the lives of those who are
lawfully pursuing their rights--including the right to free
speech--just because you and your friends all agree that they
should shut up.

As for the flooding, well, I don't know what can legally be
done about that.