hooberus
Using the human-chimp divergence and the amount of genetic differences between them isn't the only way to get an estimate for the mit DNA mutation rate. I'm not sure if you know this or are just ignoring data that doesn't completely side with your own view.
I used the phrases "generally" and "frequenty" to denote the usual phylogenetic [evolution based] methodology used in such calculations, which of couse implies other less used methods exist that don't necessarily use this assumption.
Another way they calculated an average mutation rate for mitochondrial dna was by looking at the genetic data of people (like the Aborigines of Australia) whose ancestors migrated to an area at reasonably well known points in time. So even if we put the human-chimp divergence point method aside, they can get an estimate for the rate.
Lets assume the rate from this method is faster (even ten times faster). It would still mean humans have been here longer than the 6,000 or 7,000 years believed by creationists who adhere to a literal reading of Genesis.
I'm sure if you check that you will find that these "reasonably well known" points in time, are themselves calculated by the use of uniformitarian dating, which also contain assumptions inconsistent with Biblical history to begin with.