No clue, but we are talking about the guy who removed himself from the game to keep his batting average pristine.
... if that's the only argument they have and they ignore all the instances of him playing hurt, wanting to play everyday and being forced to sit, then that is a pretty poor rationale. But that happens alot with fans sadly, the past is obfuscated and moments that happens recently are more lasting.
I wish that those fans remember that Reyes isn't the only player who has done that, and he won't be the last. However, expecting unbiased nature in sports fans off the bat in of itself is fallacious.
Maybe they are booing because he is a coward who was scared to death of losing his meaningless batting average award and quit on his team.
Then I hope the same fans boo Ryan Braun for putting his meaningless life on the line by taking a banned substance to win the MVP Award, then attempting to ruin the life of an innocent guy who was doing his job and did it correctly.