While I do not doubt that the stats are accurate in terms of being properly calculated given the particular formula that the researchers have chosen to implement,
I'd say that the report is mostly garbage. It inappropriately skews certain issues more than its intended goals and manages to ignore that the spread on DOT complaints - an average of .5-2/100,000 passengers on mainline flights - is simply too small a range to actually be useful as a barometer of anything. The metrics for baggage and IDB issues are similarly narrow.
When 17 "incidents" out of 219,000 flight operations can get you labeled as the "least safe" airline out there something is very wrong with the folks assigning blame.