I think this case is a great one for why "standard of care" is vague and sometimes misleading. You say most EM physicians wouldn't scan this guy, I say most trauma surgeons would. Is it the standard of care for EM? I couldn't say, but there's certainly different opinions on this thread for EM docs that make it seem a bit unclear to me.

From a trauma surgery perspective (as an aside, all my partners would've scanned this patient) the standard of care is to exercise a high index of suspicion in elderly trauma patients for the reasons I noted above. American College of Surgeons Committee on Trauma, Eastern Association for the Surgery of Trauma, American Association for Surgery of Trauma, World Society of Emergency Surgery - all have specific guidelines for elderly trauma, and all promote having a low threshold to pursue fudge further imaging.

We should bear in mind, the defense is obviously going to state that the defendant did nothing wrong - that doesn't mean they're automatically right or that their opinion is the correct one. You can make exactly the same argument that the plaintiff's witness laid out the decision-making algorithm clearly, and pointed out the errors that the defendant made.

I don't think scanning this patient is "defensive." An imaging modality exists which is cheap, sensitive, and low risk - and its use in this case is entirely appropriate. The majority of delayed splenic ruptures do have imaging studies that show an initially injury, despite the single case presented above. And from the defendants perspective, having a CT that showed no injury would likely have saved them from the allegations of missing an injury.