Additionally the claims they make about timezones are also only based on the difference of timestamps. Eg they see that the difference between 7z (Unix timestamps thus UTC) and RAR3 (MS-DOS localtime) is three hours. The way they then conclude it's Eastern time is very flimsy.
In fact that that alle files, even those in rar-files were all modified on the same time, convinces me more that the timestamps have nothing to do with the transmission. But that someone altered them after the hack, or that but more unlikely is that all the timestamps are still untouched and exactly on how they were on the DNC server