Having the public record of the contribution is a matter of operating in an open and transparent manner.
Attaching the contribution as either straight code or as a patch provides us with a very convenient and consistent way of keeping track of the contribution. While Git repositories are relatively durable and commits can't be tampered with, repositories do disappear, move, get merged, etc. and it's possible (however improbable) that we may lose track of it.
In more practical terms, attaching code to the CQ is relatively easy for you, but relatively time consuming for the IP Team. I think that everybody will agree that anything that anything that we can do to make the IP Team just a little more productive is better for everybody.
So, please follow the instructions and attach the code.
FWIW, IPZilla is a fairly old system that we put in place long before Git came onto the scene. We've been talking (informally) internally about an eventual replacement system which may provide us with some opportunities for better automation. We haven't opened a bug, but we'll be sure to let everybody in the community know when we're ready to start getting input into the process.
Wayne