Additionally, (and it shouldn’t be that it has to come to this, as the RaMBa”M is extremely clear in his loshon that once a person passes away they cannot be moshiach, including after a techiya,) the Rebbe ZY”A in his works about moshiach never implies that moshiach will be from those that passed away.
Furthermore, the Rebbe gave an entire farbrengen from mem hei about the job of a nosi once moshiach comes, which would seem to imply that once the nosi passes away, like any other tzadik they are not in the running for being moshiach.
Again, and I’ve said it before on this thread, if you would like ideas about how to keep the Rebbe ZY”A relevant in your life without twisting halacha and manipulating yourself, I would be more than happy to farbreng with you privately.