Sure, but if you get a judge that decides that the penalty should be salary from the time you were interviewed to the settlement date for each of the plaintiffs, the cost could be many times higher. Not to mention this simply won't look good in the public spotlight, regardless of how right Google may be.

It's also almost impossible to prove on both sides. Even if Google has insane numbers showing how many young vs old people they hire, it's totally possible that the younger ones are simply more experienced with the technologies/paradigms Google is looking for. A judge might not see it the same way though.