So, since this seems to be relevant im a CISO myself. And i would definitely not agree with everything in this letter. Personally, i think the worst part about it is handling a low probability as something that's not gonne happen. Thats, especially in IT-Sec, one of the worst practices. To take on point as example - the "never scan public QR codes". Apart from the fact that there have been enaugh exploits in the past…
It's somewhere between impractical and impossible to evaluate a URL and know anything about its "safety". So if you can't make your Web browser impervious enough to tolerate basically any crap a server may send back to your satisfaction, then your only answer is a total walled garden.