That would be a total of 60 million mutations. The actual number is around 40 million mutations that separate the human and chimp genomes:
If we are talking about the number of fixed mutations then you have to count a single 500 base pair indel the same as you would a 1 base substitution. Don’t get your units mixed up.
From what I have read, Buggs has confused lack of orthology between the sequenced genomes and lack of orthology in the actual genomes. There are gaps in the sequenced DNA for both humans and chimps, and there are also chunks of DNA that are kept out of alignments because no one knows where that DNA fits into the larger genome.
Added in edit:
There was a thread a while back where Buggs himself discusses these numbers with other posters at BioLogos:
That is correct. Neutral mutations can can become fixed with the rest of the allele when a beneficial mutation occurs.
Even your own math puts the number of mutations at 60 million mutations which is 20 million more than actually exists, according to the chimp genome paper.