Okay, so here is what kinda confuses me...
It doesn't appear that he took the bat and just beat rocks with it. It probably broke under normal stress. If you're lending a bat out, with the intent for them to use it to swing at a game, or BP... isn't that kinda expected? This is different than lending a bat out and a guy smashes it on the ground, or breaks it over a pole, or puts long cleat marks in it.
Edit: I just noticed you said it had about 5k hits on it. Well... that makes sense and probably the reason why it's cracked. A buddy of mine swung my Evo in a game, hit one out, but came back into the dugout with the bat in hand and said it cracked apparently. I looked it over. Sure enough. He apologized profusely, but realistically, I let him swing it. That's what bats do eventually. No harm, no foul.