I will trust a well respected malpractice attorney who has defended hundreds of docs (the majority successfully) instead of the opinions of other ER docs when it comes to the ways to document to prevent or defend litigation.
Nobody said that you can't be sued if you document everything. It's less likely you'll be sued according to him, and it's more likely that you successfully defend your case.
I will always document what I consider, why I didn't think it was likely, etc. As
@thegenius pointed out, doc B documented his rationale behind things and follows within accepted protocols/guidelines/standards of care. Doc A could be presented as being careless or incompetent because he never considered PE. I've been told it's easier to defend something that you considered and documented why it wasn't likely than it is to defend something you didn't mention, which the plaintiff will skew that you didn't even consider it and will point out that it's a standard consideration in emergency medicine but you're too incompetent to consider it.
Pardon the rambling. Coffee hasn't kicked in.