Peter, that's really bad advice. That'll make any subsequent script which relies on CS5 or later features not work.
Either you should wrap that in a try/catch/finally, or use version folders.
app.scriptPreferences.version = 6;
// your script
app.scriptPreferences.version = parseFloat(app.version);
Create a folder in your scripts panel called "Version 6.0 Scripts", and place the script in that subfolder.