Star Trek: Picard has established that James Kirk’s body is in the hands of the Daystrom Institute.
Star Trek: Picard has made some wild moves in its brief three-season arc, namely killing Jean-Luc Picard and putting him in a synthetic body that will die of natural causes. Genius. Due to this, Picard’s “real” body had to be moved somewhere and it turns out that it was moved to the Daystrom Institute.
While most of the core cast of The Next Generation explored, they found not only Picard’s body but the body of another great captain, James Kirk. Kirk died during the events of Star Trek Generations, after a catwalk that he was on broke free and went careening down the side of a mountain.
His body was buried by Picard and was apparently later taken by Federation officials to the Daystrom Institute to be put on ice. But why did Picard showrunner Terry Matalas decide to bring Kirk’s body back into the fray?
"Look, it’s not how I would have sent Kirk off, clearly, because I just put his body in Daystrom.…Look, Kirk is dead. We figured, “Is his body really just under a pile of rocks on that planet?” We’re not committed… we’re not saying he is resurrected."
It makes sense that Starfleet wouldn’t leave valuable assets lying around
While it may not make many fans feel all wholesome inside, the facts are that if someone discovered genetic material of James T. Kirk lying around, that could prove to be very bad for the Federation. In an age of resurrections, cloning, and lord knows what else, leaving a body lying around on a planet ripe for exploration and potentially terraforming is just a bad idea.
It makes total sense that someone would come back and take Kirk away and protect him, even if he was long dead.