My question is in regards to this question: https://askubuntu.com/questions/540665/packet-traversal-through-ubuntu-kernel
This is a question about the nitty-gritty underpinnings of the linux kernel. While, technically, related to Ubuntu it's not really Ubuntu-specific. this question on meta leads me to think the proper place is not here but on unix.se instead.
A whole ton of things that are roughly related to the Ubuntu project (including software it includes and development on it) are explicitly on-topic here. Your example meta question is looking for the best place for generic questions. That's quite a different question than asking if something is on-topic or not.
The question is quite broad though. It wants a blow-by-blow of Linux networking; something you'd usually suggest somebody read a book or two about. It is probably answerable at a high level by somebody who really knows their Kernel networking.
Short answer, it's probably on topic but possibly not the best fit for the Q&A format. I'm perfectly happy to let time sort this out.
linux-kerneltags for Unix & Linux and Stack Overflow. AU isn't anywhere near the top set of results.