I was just trying to disable a menu item based on whether $2 exists or not and it was found that $2- doesn't exist in the menu item text although multiple nicks have been selected:
menu nicklist {
  $iif($2 != $null,$style(2)) EWhois:whois $1 $1
Try this yourself by selecting multiple nicks and then checking the menu.
By entering $1- into a custom alias within the $iif (e.g. $iif($check($2),...)) you can echo the input to see only $1 is returned.