No possible way. Sherlock understood what that meant even if Mac wasn't saying it straight out. It meant that she'd sent the message and shot herself mere moments later. Unless he'd been able to travel instantly the second that he'd gotten the message open, he'd always have found her exactly the same way. If he'd arrived earlier, he'd merely have had the zombies to deal with as well even if he'd managed to avoid most of them by traveling over the rooftops on his way here. "She wouldn't have," Sherlock affirmed Mac's last statement before taking a deep breath and storing his PDA back in his pocket. "Obviously I'm not needed on this scene," He said, standing straight backed and making his statement as professional as any other that he could have made. "But I hope you don't mind if I stick around until the coroner's van takes her away," He said, glancing back over at Mac. "To examine the place, obviously."
Not that he really needed to make an excuse for why he wanted to stay with Mac, he was sure, but it was better to give the man something to say if anyone else happened to show up and question his presence.
Moving over to where Mac was standing, Sherlock's gaze was drawn momentarily by the book on floor, the title provoking not only confusion but another brief blossoming of guilt in his chest. Not that he could entirely blame her for being curious, he couldn't help but think that if he'd been here, she wouldn't have needed to look for substitutions for the genuine article. "Maybe make a few mental notes about whether everything was so that it can go back in the same places after the clean up."