I would highly doubt he would get rehired today at google first try. Leetcode is a different beast and things might not be all that fresh. Someone on the hiring committee might have said yes too many times this month.
I'd be extremely surprised if Jeff Dean (at any point in his employment) would fail a SWE interview loop at Google. The Google interview is heavily based on data structures and algorithms, and Jeff Dean likely knows them cold.
Sure there's always a degree of luck, and Google errs on the side of false negatives, but there are certain people that are so high above the hiring bar that luck becomes too tiny a factor to be relevant.
That's pretty much what Leetcode is. When I interviewed at Google I was asked tree traversal and hashmap design questions that were very similar to leetcode questions.