Enforcement is a problem because no agency has legal authority to do anything about such advertising. The only thing they can do is keep the expelled instructor from certifying students. The TripAdvisor comments mention another individual who may also be a PADI instructor. If so, then the company can still offer PADI instruction through that other instructor.
Another factor is that there is a difference between a dive shop being PADI-affiliated and a dive shop offering PADI instruction through an employee or someone they happen to know. Many years ago, before I was a professional, I reported the worst standards violation I have still ever seen (in Fiji). I got a lengthy response from PADI. It explained that they could only take steps against the instructor (which they did), but the shop was also advertising themselves as a PADI shop, which they were not. There was little PADI could do about that, since they could not control the laws in Fiji. They told the shop not to advertise themselves as a PADI shop, but they had no power to enforce that.
I saw a similar thing in the United States a few years ago. I noticed that a dive operator in Florida that I used frequently had a sign in the story that advertised them as a GUE instructor training facility, yet I never saw them provide any instruction other than through SSI or TDI. I asked the manager about it, and he explained that while no employee of the shop had any GUE instructor credentials, if you wanted to get GUE training, they had the necessary phone number and could call a guy who could provide it. That was apparently fine with GUE.