From Chapter Fifteen of Rabbi Shloma Majeski’s Likkutei Mekoros, Volume 2 (Underlined text is the compiler’s emphasis.)
Translated by Boruch Merkur
In the sicha of Shabbos Parshas Tazria U’Metzora, 6 Adar 5751 the Rebbe cites the saying of our Sages, “If he is among those who are alive now, certainly it is someone like Rabbeinu HaKadosh.”
In the footnote on the words, “those who are alive now,” the original transcript of the sicha read: According to the ruling of Rambam (Laws of Kings, Ch. 11, end), “If a king rises up from the Davidic dynasty, etc.” – “the inference here is that he is ‘from those who are alive now.’”
The Rebbe Shlita crossed out several words [“the inference here is that he is ‘from those who are alive now.’”] and wrote (at the end): “meaning that he is already a king” [suggesting the possibility of Moshiach being from those who are not presently alive].
(From the handwritten edits of the Rebbe on the sicha transcript)