The parks are for-profit businesses and have put together plans to open in other states. VA isn't special. The 1000 person cap is arbitrary and has little relation to science, unless you want to argue uncapped capacity on bars is a good idea. Nearby MD and PA have a 50% capacity rule, but not the arbitrary cap, so their parks will actually benefit at VA park's loss.Is that a responsible gesture when the whole reason the parks aren't opening or have strict guest rules and/or lowered capacities to help lower the chance of spreading the virus?
I don't think it is, especially when all that gesture accomplishes is to increase potential spread at open parks, and possibly take that many more slots needed in the reservation system. Plus those parks wouldn't necessarily see much extra revenue from upgrading people to a multi-park pass.
I assume Cedar Fair and SEAS are going to fight this, whether via lobbying or a lawsuit. If they are unsuccessful with that, as a token of good gesture to their customers, allowing them to visit other parks isn't a bad way to show goodwill with their customer base and maybe keep them from getting passes at other parks (e.g. Six Flags America).