If it could be closed right away, wouldn't you do that before you print it out? Perhaps I'm a luddite, but wouldn't typing the ticket number into a box almost certainly be faster than getting your phone out, turning it on and scanning the code?
Heh, that's in the article under _Wrapping up and next steps_
> For the tickets themselves, a QR code could be added to link directly to the issue on GitHub. You could also add in more details from the issue itself like tags and severity.
The printers unusually can create barcodes and some of them also QR codes.
But it is also possible to print images. You can also configure them as standard printers and print via any common printing system (cups, windows spooler, …)
Then could scan with your phone to bring the issue up for immediate triage. I imagine lots of issues can be closed right away (or very quickly).