God, it's bad enough to release domesticated rabbits outside, but to DROWN them?? Releasing them may be a virtual death sentence, but they'd at least have a slim chance of being spotted/rescued and even if they didn't, drowning is one of the worst, suffering-filled ways to die!
Seriously, why get rabbits in the first place if you care so little about them? And why not just dump them off at a rescue?? People are horrible, especially ones that actually *enjoy* torturing/killing animals (which that guy probably does - if all he wanted was to be rid of the bunnies, then why be pissed off at someone for taking them from him).
It's so nice to see the other side of humanity, though - a woman who was attentive enough to pick up on somewhat subtle clues that something very wrong was going down and who disregarded her own safety to snatch the sack of bunnies away from a man prepared to murder them (though I imagine if he'd tried to hurt her, her dog would've rushed to her defense, which may have been why all he did was swear and storm off). Dog or not, it was still a big risk and she didn't hesitate to take it in order to save innocent lives.