We can theorize about that for days, but the truth is that no one knows if any of it is legal or illegal.
There is no federal law and every year they try to pass one but it never happens.
The World Trade Court has ordered the US to stop discriminating against casinos located in Antigua and Barbuda.
There is a court case against the US by Casino City – and the papers for that were in New Orleans where the next level appeal was scheduled to be. This is going to delay the process a lot since the courthouse was apparently flooded.
Those who say casino and poker gambling online is illegal have nothing to base that on. If you say it’s legal, you have nothing to base that on either.
So we are back to: Nobody knows!