This is exactly what I was trying to get at! Why call 911?
She had not left the house when he called 911 - she was in the house (according to him). She left after the call.
As to the idea that "there's blood" in most DV situations where 911 is called - what is your evidence for that? Is there a study somewhere I can look at?
People seem to be assuming that because THEY don't think they'd ever call 911 for a DV situation unless their life were in danger, that there's no way JV would have done it. He's not you, and if you've never actually been in a DV situation you can't really know what you would or wouldn't do, or when you'd call the police.
There are plenty of DV cases in which someone (male OR female) is merely being threatened and feels unsafe, and they call 911 to defuse the situation. It's also done as a reality check on the abuser - the police show up and that makes it clear that what they're doing is not justified or normal. Finally, if there's a log of the call and the consequences, and the police are called again or there's any sort of legal action, that paper trail will follow the abuser.
I'm not saying whether I believe JV's story or not. (I'm about 65/35 it's not true/it is true, for what that's worth.) I'm saying that second guessing his call and saying it makes no sense is ridiculous. Female-on-male DV happens all the time and while it may not end with lethal consequences very often, it does cause emotional/mental anguish and trauma. And the men who do report it are sometimes mocked and belittled because they aren't "man enough" to protect themselves or stop the woman from doing it. Please don't contribute to that viewpoint.
Dismissing his story out of hand also negates other experiences of DV as being "not dangerous enough" to involve the police. What you think is "dangerous enough", sitting behind your computer, is hardly realistic, compared with someone actually going through DV.
If all of this took place, it did so in the heat of the moment, and people do things in the heat of the moment that they'd never do when emotions aren't running the show. Like call 911 on their partner, or leave the house without their phone. (FWIW I've left the house without my phone plenty of times, when upset and when not - it's not the case that everyone on earth is obsessed with their phone to the degree that they carry it everywhere.)
tl:dr - JV's story may not be true, but please don't belittle all male DV victims by acting as if you know better than they do, or assume everyone reacts the way you think you would in a situation you've never been in.