It seems technically Frank was not "in the house"
Frank Chiziweni, a Malawian immigrant who lived in an outhouse next to Mr Pistoriuss kitchen, told police he had slept through everything.
So Nel is correct in his statement.
This is the danger of Masipa copying and pasting defence submissions from the HoA
Clearly there was someone else who could have shouted out - e.g. to call for help.
Your quote that I have highlighted in bold, that's from a newspaper report if I'm not mistaken. I'm not convinced that it's accurate.
Early reports had Frank living in a detached building somewhere in the garden, but there doesn't seem to be any such building.
I think it was later established that he had a room off the kitchen, which may have its own access, but is still part of the house.