I wouldn't have allowed myself into a situation like that, guaranteed. Most of us probably wouldn't have.
After all, was he placing himself in danger of being shot? If he put himself in front of a potentially hostile silhouette (one presumably with concealed/unseen hands), then that's exactly what he did.
Why would he do that? Why did he process it so incorrectly?
In the end, however, it's his property. Westbrook was the one who was misplaced and unable to explain himself, and he used his presence in a way that could be perceived as threatening.
As the story stands so far, that's the way it is.