I Think he can get loads of devil fruit coz his body's all different and stuff. My theory is that he's actually a cow who looks like a human and so he has multiple stomach compartments. obviously he's not digesting his devil fruits and he's just keepin em in some of his stomachs. That's why.
or He keeps the DFs in a pouch on his stomach because he's secretly Marsupial D. Teach.
Let's here some funny theories