Technically no. The beaches are all public property and drinking alcohol is prohibited.
That being said, we saw a lot of drinking on the various beaches around the entire island. It's possible the law is in place to crack down on those consuming too much and this gives them a way to kick those people off the beach. Not sure.
What's a little strange in Hawaii is that private parties can't own the beach. The beaches are all public property, so even though a resort may claim it has a private beach, the beach itself is public, the resort just may make it difficult to get to it through their land. So, even though Aulani has dozens of chairs set up on the beach, anyone can visit and use the beach and the Aulani owned chairs. You do need a card key, however, to get back to the buildings and the pool/lazy river area.