Whatever. It just proves that you can't control a virus.Wrong. All recruits about to start boot camp are quarantined via a standard protocol (true in the other services as well). From the original study:
"The public health program implemented by the U.S. Marine Corps for all new recruits includes a period of home quarantine followed by a 2-week, strictly supervised quarantine at a closed campus, with the objective of mitigating infection among recruits."
The study team merely selected a group to monitor closely. Boots who signed up for the study were mixed in with the full population so there couldn't have been a difference.
The difference in outcome between the two groups was not statistically significant.
2% or so positives during the quarantine is right about the max that has been seen across the services. Sometimes it's zero. The quarantine is in place to avoid large-scale infection during boot camp. Earlier efforts that involved direct accession, albeit with testing, resulted in much bigger problems with both the recruit population and training staff. Military readiness largely runs on maintaining the through-put of accession pipelines. The services have done an admirable job of maintaining that flow during the pandemic.