What the hell are you talking about? It's a PUBLIC marina. Wanna bet there's some gay group who is enjoying free use of public property because of Berkeley's arbitrary rules? Plenty of not-for-profit groups are discriminatory. Do you really want to open that Pandora's Box? The end result of rulings like this will be "mo more Boy Scouts." Is that a good thing in the name of buttsex equality?
You're actually making a very good argument that a "public marina" shouldn't even exist in the first place. That rationale should also be extended to just about everything else we've come to expect from government these days -- public schools, public hospitals, public housing, etc.
If the scouts can show that there are other private groups that discriminate in their membership but who still receive some form of benefit or subsidy from Berkley then they can claim discrimination on their own, and then that could lead to a USSC review. Doesn't sound like they made that case here.