I think what they are saying is the "9 MM" or any other pistol, be it 38, 357, 40, or 45 will save your life, what they are saying is any pistol/revolver wont save your life unless you learn how to use it.
Frontsight is advertising, and any business does (or should do). They aren't saying anything about a given cal. they are saying, you need to learn to use what ever pistol cal. you have.
That's just my opinion.