Personally, I would be more concerned if someone with malicious intent and the ability to keep silent about what they have done had found & exploited this. [0]

Advertise: remove your competitor from Google's search results for a day! If I didn't think it was illegal, I'd probably pay for that, were I in such a situation.

[0] If, of course, it even existed in the first place. It seems plausible enough to me, even if I think it unlikely.

Eh, ok it would be more concerning. But Lulzsec would have made quite a spectacle out of it.

Now that, I must agree with.

How do you know they haven't?

I think they would have said about it already ;).

I think Google would be the last place they look for vulnerabilities.