Running an ad on mobile for a site that's not optimized for mobile is a HUGE red flag, not some afterthought that should be mentioned in the conclusion. I'd wager anything most of Facebook's traffic comes from smartphones and tablets nowadays.
The interesting thing to note is that he has different results for people that come from Google - maybe people have different expectations about the website depending on whether they're looking for it on Google or just sitting in an app like Facebook?
