Well yes and no.

Since the channel would currently stored in the %stopjoin variable the bot wont be in the channel. But what you could to is send a private message to the bot having !allowjoin <#channel> remove it from the list then join the channel.

This can be achieved by:


Code:
ON *:Text:!allowjoin &:?: {
  if ($istok(trollman118 Panic,$nick,32)) && ($istok(%stopjoin,$2,44)) {
    %stopjoin = $remtok(%stopjoin,$2,44)
    join $2
  }
}