But that's not how Aikido works when someone is trying to stab you, because its a competition, so the range of techniques you are allowed to perform is limited, and there are rules you can game.
So while it is a bit more intense than what is normal tanto dori practice it still not even remotely close to what a real knife attack would be.
Strictly speaking that is "how Aikido works" though, isn't it? It's just that it's applied to a very limited setting. A lot of things are practiced with rules: are they all unreal (i.e. unrelatable to real life situations)? I think it's more correct to describe it as non-comprehensive rather than to suggest that all attacks will never look like that.
...I'm probably just nit-picking the language though.