Either what Matti suggested or to use a list of nicks, you can modify it to this.
Code:
on *:text:*triggermessage*:#: { 
  if ($istok(%blist,$nick,32)) { return }
  if (!%delay) { 
    set -u1800 %delay 1 | .timermsg 1 $r(20,300) /msg $chan replymessaget 
  } 
}

And put the nicks you dont want to respond to in %blist smile