TFA complains about browser intermediate cache behavior but doesn't seem to realize that if you're relying on browser intermediate caching at all, your server is misconfigured. The lesson should be "fix your server", not "those darn browsers."
Once the missing intermediate certificate issue had been identified, the fix (to the server) was indeed clear. But it's not stated whether the author is in charge of the server in question (it's only mentioned as “couldn't connect to a particular HTTPS site”); I suspect this was some external web site not under their control.