It's a bit of a weird one. Quick items (and other confirmation-skipping stuff) is allowed because it's you making the request, not the script/website.
Usually when you try to use an item, it brings up a confirmation; the "use" button is just cosmetic and only serves to bring up the confirmation, making no requests; only the "yes" on the confirmation sends anything to the server. Quick items are basically equivalent to moving that confirmation "yes" button to the top of your screen so it's always there.
This makes it okay so long as it's on the same page (so quick items are always on your item page, or on faction's armoury page; you can't e.g. have a "use medkit" button on someone's attack page) and so long as it's always one user input per request (so you clicking it once only uses one of the item, you can't have a "drink 48 beers" button).
Similar idea with quick-busting/bailing (only the "yes" on "are you sure you want to bust...?" is a request) and there're some for skipping the confirmation on item market purchases too.