If somone goes into the majority of dojo's in america and tells the sensei they are there for self defense, they will usually be told that their art can make you invincible (more of less).
I myself have never heard this. And I practice a fairly rigorous style of aikido. But my teacher, the senior students, the visiting shihan...none of them have ever made this statement or anything like it.
I suggest that you are pulling our legs. The alternative is...