They're a bit vague when describing the "I-was-going-to-buy-it-anyway" problem, but it sounds like they're mainly talking about PPC ads on search engines stealing from SEO links on the same pages. (Some of it seems to be talking about stealing sales from the direct channel, which I have no idea how to handle.)
If your website is already tracking ad performance on a per-ad basis (i.e., tracking all the clicks on that ad, and keeping what you pay per click below what you're getting per click), then optimizing for only the paid search traffic that's incremental, and not cannibalistic, is pretty straight-forward, conceptually.
For a given ad's keyword, instead of optimizing only for the results you get from PPC traffic, you treat your PPC bid as an input that affects sales across PPC and SEO traffic for that keyword, and optimize accordingly.
There are a few extra steps and decisions that need to be made before full implementation, but this is the basic idea. It's actually not too bad to account for.
If your website is already tracking ad performance on a per-ad basis (i.e., tracking all the clicks on that ad, and keeping what you pay per click below what you're getting per click), then optimizing for only the paid search traffic that's incremental, and not cannibalistic, is pretty straight-forward, conceptually.
For a given ad's keyword, instead of optimizing only for the results you get from PPC traffic, you treat your PPC bid as an input that affects sales across PPC and SEO traffic for that keyword, and optimize accordingly.
There are a few extra steps and decisions that need to be made before full implementation, but this is the basic idea. It's actually not too bad to account for.