why \"if ($nick [b]iswm] %myowner) {\" ?

someone could simply use a similar nick to the owner and delete every word ... and for the other if\'s, u should use ==

No, not really. It would have to use $+(,%myowner,) or something similar to match the nick. Just %myowner would make the script make sure it was positively %myowner.

Try it using something like this:

alias testnick { 
  if ($1 iswm Rebellious) { echo -a Match! }
  else { echo -a No match! }
}

/testnick Rebellious would return Match! while /testnick Rebellious1 would return No match!

But yes, this snippet has a LOT of room for improvement.