Nor should people be awarded karma for being right for the wrong reasons.

Of course you can discuss his motive. But it is a logical fallacy to use his motive to disprove his statement. The person I responded to said that since he showed motive, his ad hom attack wasn’t fallacious.

If someone without his proposed motives had made the same statement, the statement wouldn’t be more or less true.

They're using the fact that he said it as a point in favor of it being true.

However Thiel has a vested interest in making Google look worse. They're a competitor.

He wants to say that Google is no longer innovating and then uses a thin excuse to validate his claim. And we're supposed to trust his reasoning. But all he's really done is back-fitted a reason to his conclusion. He wants to believe that Google is no longer innovating, so he picked something Google is already doing and claims that that is evidence.

The first step would be to define "innovation" in a way all relevant parties can agree upon. Then we need to agree on the things Google has done that would qualify as innovation. Then we can plot how much innovation they've done then compared to now.

No, it's used to encourage skepticism of his factual claims.