It's a reference to the Bruce Wayne: Murderer and Bruce Wayne: Fugitive storylines from around the turn of the century. Bruce got framed for murder and his then bodyguard/crime fighting partner in training/love interest Sasha Bordeaux got pegged as an accessory, since Bruce's kinda crappy alibi for the murder was that he and Sasha were beating the snot out of criminals at the time. Bruce got jumped by three thugs and he wrecked them. Worried he'd out himself as Batman, he broke out leaving Sasha behind. She got shanked and Checkmate saved her, giving her a new face. A bunch more stuff happened after that, and Sasha became super awesome and a major player in a short-lived Checkmate comic.
There's a huge amount of backstory leading up to the event and following it, but the long and short of it is that Bruce proved yet again that he'll protect everyone except the people he supposedly cares for most. (read: Jason, Sasha, Barbara, Damian, the Justice League, pretty much everyone he's teamed up with ever. Also he almost ruined the whole world with his Brother Eye shenanigans.) I may or may not have issues with Bruce Wayne being kind of the worst.