I don’t think a winning write in candidate is acceptable if they are not in the end willing to prove their eligibility.
I think a write in candidate, would have a hard time winning. But, if he gets the most votes, then the next question will be will the electors actually vote for him? That is the constitutional question you bring up. Buth this question won’t happen to deny anyone from writing in a candidates name. That is the freedom to vote for whoever you want, even Mickey Mouse. So you can’t stop someone from writing in Barack Obama, but that doesn’t mean he will get the electors vote. That’s when the real constitutional fight begins.
edit - I think a write in candidate, would have a hard time winning. But, if he gets the most votes, then the next question will be will the electors actually vote for him? That is the constitutional question you bring up. Buth this question won’t happen to deny anyone from writing in a candidates name. That is the freedom to vote for whoever you want, even Mickey Mouse. So you can’t stop someone from writing in Barack Obama, but that doesn’t mean he will get the electors vote. That’s when the real constitutional fight begins.
edit - Because the 2nd place finisher will have STANDING, and will challenge the eligibility.