The debris that you have shown are mostly spherical and most probably were helium bottles made from Ti, which is very strong and heat resistant. Such bottles are known to be able to survive re-entry. Except for the space capsule, which has a heat shield, they are all damaged by heat and/or by impacts. That pipe doesn't look damaged in any way to me.

And can you show evidence that that pipe was indeed from a LM5 core stage falling from space? I am still willing to accept such a theory if there is evidence. Mere suspicion does not prove anything.