Actually, kibble digests faster because it's been cooked and processed. The risk of salmonella infection is the same regardless of whether you feed raw and kibble in the same meal.
Screenshots or it didn't happen: DIGEST THIS: Kibble May Actually Digest Faster Than Raw | The Raw Feeding Community
I must have missed your link earlier, but I think it's awesome that someone took the time to collect actual data on this! That website is pretty cool - it's nice to find a group of raw feeders who actually reason through the evidence behind the claims that they make.