Installing such a modification is in no way different than enabling the cache on a browser (which most browsers do by default). Like that modification, the browser stores images for ease of browsing. :P
Images cached on your hard drive which may never be used again aren't in the same league as images republished on your site for others to see (and from which you might be making a profit). Do try that argument in court and let me know how it goes.
Quote:
But I assure you my intentions are genuine.
Your intentions are to auto copy images from third party sites without any check on copyright... and then republish them.