I suspect that Beltran was the only one named because he's the only one who's no longer an active player. Even though players were clearly involved, it seems like MLB wants to lay all the blame on the management level and put the punishments on them. It makes sense to that end to not name other players in the report so as to not brand them with a scarlet letter and raise the ire of MLBPA.The mention of Beltran is really weird because there was no need to do it. The relevant quote is "Approximately two months into the 2017 season, a group of players, including Carlos Beltrán, discussed that the team could improve on decoding opposing teams’ signs and communicating the signs to the batter." Why include the bolded? Presumably the group "included" a bunch of players. All this does is fuck over the Mets because now everyone is asking how they can continue to employ as a manager someone who was definitively involved in the scheme.
The conspiratorial view of this is that MLB knows it can't suspend Beltran alone because it would raise the question of why other players weren't also getting suspended, so it's passed the buck to the Mets to make a disciplinary decision. The ultimate question is, if Beltran were just enjoying his retirement in a villa in Puerto Rico somewhere, would he have been named in the report at all?
Frankly, I don't see why the Mets need to be under any pressure to discipline Beltran for something they had nothing to do with. If they want to re-think the hiring based on this new information, fine. But if they see it as activities as a player that won't impact his ability to manage their club, they're perfectly entitled to keep him on. I mean, teams have hired Mark McGwire and Barry Bonds in coaching roles despite their PED allegations/admissions. Should they not have for fear that they might corrupt players into using PEDs themselves?