Two major reasons to avoid kidney beans, toxic phytohaemaglutinin levels and high protein levels. Additionally, most beans have large amounts of added sodium.
Even cooked, rinsed and frozen, large beans can cause hormonal and kidney problems are considered large beans.
If you must serve canned beans to your bird, serve rinsed black beans or smaller with no sodium added.
The plastic liner can leach into beans over time, so it is best to serve rinsed and home-sprouted beans instead. Also related, two reason you were told not to buy dented cans are, again, the leaching process (Metals can be dangerous.) and dents can loosen (even slightly) lids meant as protection.
Certain widely known AVs (2, I think) back serving smaller beans canned without added sodium and well-rinsed because of their natural proteins but the vast majority do not. Also, these are in medium to large birds, so much depends on your bird as well as your choice. But all agree that large beans should not be served.