For one thing, "human" randomness is not random enough since we just replace numbers with more predictable ones, unlike a computer. And I'd be hard-pressed to find a private key that happens to have what I call "human randomness" entropy/bits in it.
I typed what I typed, was blindly hitting the keypad, deleting, adding, without thinking. Hard to call it a real randomness but still..
BTW, one might think there's a trick, lets say, I used one of my old private keys which I entered into their search. But the thing is that that website doesn't show you the page the key is on when you enter one. You can enter your old private key, it will show you calculated public key and other stuff, but it doesn't say which page it is on. So as strange as it is, looks like I did the impossible?