The links you gave didn't support your attribution to Yihi regarding USB charging. Thus, the only conclusion that can be made so far is that you're asserting your opinion as if it is YiHi's. As to what they recommend, I leave that to the manual, which someone else has already posted. Also, as to what constitutes a passthrough, it's generally the feature not the exact function that matters. So long as the device can be used while charging, this is often referred to as USB passthrough. Should you need convincing on that, just do a google search of any popular recent mod (e.g., istick) along with the term "USB passthrough" and you'll see that is the case.
The ability to use the device while charging is listed as a feature (or capability if one prefers) in the manual. As to the rest of your hyperbole, such a failure would be due to using a defective battery. The charging feature itself, however, is unlikely to cause any thermal runaway, as it is below 0.5 A.
A true pass thru was a device back in the 08-09 era that screwed on your cigalike type of device in place of the battery so you could vape with out a battery. That way you could vape and not use your battery up. It was a handy little device since the batteries then were only good for about 2-3hrs so if you didn't mind being tethered to your computer or wall socket you could vape away to your hearts content on your tea bag carto. And you weren't vaping something that can possible pull 20 or more amps.