I think the original poster said that even his free Home version detected infected javascript in Opera - in spite of the fact that Opera is not supported by the Script Blocker, and even though the Home version doesn't contain the Script blocker at all
Well, if you have the Standard Shield sensitivity on high (or modified its particular settings), it is possible that Standard Shield detects infected scripts when they are written to (or loaded from) the Opera cache (i.e. from disk).
The Script Blocker, on contrary, scans the scripts directly in the (supported) browser - i.e. it works even when the browser doesn't write the file to its cache.