A good point and you're quite right, the mod removes the image from a quoted post on a post by post basis rather than by running a dB query to achieve the same effect.
If you care to come up with the dB query code to do it, I'm happy to modify the mod and give you credit for that work.
Personally I don't think it's necessary as it would involve running the query for every quote made to check for an image and remove it, this might push up the overhead on the server somewhat.