I don't think it will win in any court because the virus is everywhere and it's invisible the accuser will have a hard time proving that he really gets the CoVid in the facility, they could have got it in their homes in while travelling while in the market or while in the street it's hard to established the fact on this case but I don't like casinos open at this point of time people should only stay home and restrict their moves.
If the government allowed businesses and casinos to open now, there are also protocols that need to follow. And even if it's hard to know where the virus came from, if the casino shows that they are not following the protocols imposed by the government, their business can also be in danger. Even if they started to operate again, they are obliged to follow the rules.
In my country, when people upload a picture showing the lack of social distancing and such in an establishment, the business can get a warning and fine from the authorities, so I think it's the same that's why small casino operators are afraid that they might get a lawsuit. But if they're following the protocols, they shouldn't be afraid of it.