I think his point is that, if invalid clicks is all it takes for an adsense publisher to get banned, then there is nothing to stop your competition from going onto your site and clicking a lot of your ads or get a botnet to do it and get you banned.

If it is a mere algorithm, then it is not unforeseeable, that, due to no fault of your own whatever, but malice of competitors, you can get banned, though, in these cases, I think there would be a good legal argument, not least because the google contract you sign up to is not entirely recognised by some courts, but replaced in many instances by what is or seems reasonable, as, when you sign up to the contract you have no choice but to sign up, thus, there is no equal bargaining power.