For that to happen beams must get past her skin durability to have an impact on her organs
Or you know same principle applies to Queens attack? It would be easier to have an impact on brain with Queen landing directly on her than those tiny metal beams landing all over her body considering how much fat she has
You're not really getting the point
Big mom's skin, as durable as it is, it's still just skin
It can stretch, kid can apply enough pressure to reach her inner organs
Think of it like this
Kidd's metal pushes big mom's skin, big mom's skin pushes her body, her body fat then pushes her organs
Also uojrr you're forgetting a big mom detail, kidd's magnetism is ridiculously powerful, so powerful in fact he can keep the metal from tearing apart