I'm not sure if you meant
if (myfriend !isin $nick) || (fishbot !isin $nick) { -> kick + ban other user )
or
if (myfriend !isin $nick) && (fishbot !isin $nick) { -> kick + ban other user )
If it's the 2nd one, just add an else { ban # $nick 2 Banned for not having the right nick }