It's irrelevant to the outcome "as a matter of law," I agree with that.
If he's found eligible, some voters will reject the SCOTUS holding, and withhold voting for Cruz. He's damaged to some extent, no matter what.
And if he's ruled eligible, SCOTUS is going to have students of the law looking at the decision as a pivot point, like Wickard v. Filburn is a pivot point. A reversal of the rule stated in every case that came before.
No I do not see him as damaged goods for sure, but you may be correct about others. However, I believe that is most likely because they support another candidate already anyway.