He has the same regen as Madara and Hashirama, they are all equal. He didn't grow another arm. Madara gave him a spare zetsu arm. He can regenerate it if it's not cut off. But if he loses the limb, then he's going to need a zetsu transplant like Madara. Your panel proves nothing. All he (Obito) did was regrow the tissue (muscle, fat, skin, bone, etc.) but it was not cut off like in Madara's case.