And some other casinos remain to run and open their physical casinos. That is because they couldn't wait a little longer for the curve to flatten. And also, the development of a gambling site could take a month to finish as they need to beta test its feature especially to match the platform to their physical casino.
When all the other businesses are open, I think that it will be unfair to expect that the casinos remain closed. Most of them have remained closed ever since April. If you don't allow them to operate anymore, then the small and medium sized ones may go bankrupt. Even if the business is closed, they still need to pay the taxes, rent and utility bills. The curve is not going to flatten anytime soon.. so there is no point in not allowing them to open.