Says who? The court?
Well, it sure beats the prior "logic" of Congress deciding what's constitutional.
That wasn't the logic prior to Marbury, either. Both types of "logic" are fundamentally the same in that they're completely circular. "So-and-so [fill in the blank] says they're the final arbiter of the Constitution, therefore they are". Why do you cling to that type of reasoning?
Oh, I don't know. Maybe because it's worked for 200+ years?
Plus, an overzealous USSC can be reined in by either the Executive branch or the Legislative branch, if necessary.
So what's your problem, other than you like to whine a lot? You got a better idea, let's hear it.