Printer on port 9100 and still prints on paper

So the script dont_print_on_printers lists the common pjl ports.
My hp printer on port 9100 is still printing on paper, is there any particular reason this happens when the code clearly shouldn’t allow this to happen?

@cfi I see that similar issues:Scan causing unexpected printing on Toshiba Copier/Modify Scans
Is there any reason that this happens ?

The reason(s) were given in the referenced topic:

As excluding the raw printing port is only done on a best effort there two more reliable possibilities to avoid such situations:

  1. Remove any paper from the paper tray before scanning the device
  2. Exclude the raw printing port from the port list used for the scan