Also, I think the main argument would be whether Moshiach can be from the meisim or not, I’m sure most wouldn’t say he was Chezkas Moshiach.
It’s quite clear that he can’t be dead.
This wasn’t a possibility before gimmel Tammuz, otherwise his death wouldn’t have been such a shock. After gimmel Tammuz, three quarters of Chabad rewrote the Rambam.
Yes, this is halachically problematic.