Yeah, I have to say I have no interest in working with a horse that is that aggressive. And to be honest, probably don't have the skills either. It's easy to say we'd do this or that, but I think reteaching a horse that messed up is harder than training it right in the first place.
My dad has a somewhat pushy horse he bought from a horse trader. We have no idea who the previous owner(s) were, but someone either spoiled the hell out of the horse or abused him (or maybe both). He's actually turned out to be a really great, quiet saddle horse. Beginners can ride him, I can pony colts on him, and he's an absolute pro.
But I don't totally trust him on the ground. It's too bad, because I think if he'd been handled properly from the beginning, he likely would have been a good kid's horse. As he is, he needs an experienced owner to handle him for simple things like deworming, even though he's quiet under the saddle.