The study itself warns it was a small sample set and thus a small number of infections, and at that level it's possible a number of cases of illness sufficient

The study itself warns it was a small sample set and thus a small number of infections, and at that level it's possible a number of cases of illness sufficient to change the risk ratio were missed in either arm of the study, since they were essentially self-reported. Furthermore, because it was a strictly pediatric study, it would be very iffy to generalize this to adults. But let's go ahead and stipulate the conclusion is true. The takeaway message is not to _not_ protect against influenza, it's to find better ways of protecting us from the other seasonal respiratory viruses. Relying on viral interference as a way to avoid infection is like starting a fire in your house to avoid the wildfire outside.