[class$="<userid>"], [class$="<userid>"] *, [class$="<userid>"]  :link
+, [class$="<userid>"]  :visited, a[href$="=<userid>"]  { display: non
+e; }
[download]

This css rule occasionaly hides responses to the troll, too (e.g. in Recently Active Threads).

update: to mark troll posts as such in threads

[class$="<userid>"], [class$="<userid>"] *, [class$="<userid>"]  :link
+, [class$="<userid>"]  :visited { display: none; }
a[href$="=<userid>"]:before { content: "a Troll: "; }
[download]

_($_=" "x(1<<5)."?\n".q·/)Oo.  G°\        /
                              /\_¯/(q    /
----------------------------  \__(m.====·.(_("always off the crowd"))."·
");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}