Proximate cause "is a cause, which, in the natural and continuous sequence, produces the death, and without which the death would not have occurred." Commonwealth v. Rhoades, 379 Mass. 810, 825 (1980),
Suppose a) the guy deserved to be yelled at least a little bit and b) the amount of confrontation would in no way be expected to cause a normal person any heart problems at all?
If the security guard acted in a textbook appropriate manner and the plaintiff still had a heart attack due to the stress of even that interaction, would the security still be liable? I don't see how that could be.