[sheepmullet]

Did you read the paragraph directly above the one you quoted?

Your quote is referring to the study where - "used a gun for defense during a situation in which they thought someone “almost certainly would have been killed""

In context the sentence you have quoted simply means the researchers could not be certain that the participants would have died if not for the gun defence.

It is in no way suggesting that they were not legitimate uses of self defence with a firearm.