Shoot. Now you can count this as a bug fix/feature request to be able to use frameworks in Smart Rule-executed AppleScripts!
As per the discussion over here (Stream annotations from your PDF reading sessions with DEVONthink - #32 by ryanjamurphy), it’d be nice to be able to use ASObjC to interact with PDF annotations directly, rather than through Summarize Highlights. Unfortunately, because of the crash highlighted in the present thread, this isn’t possible in Smart Rules.