This is a very sticky wicket. Being trained is one thing. Being an off duty LEO is another and attempting to help in a situation you might not understand might have you attempting to subdue the good guy as opposed to the bad guy. I don't know that there is a good answer for this question or not.
He was only responding to fact that the op stated he clearly would not use his weapon to save someone else in any scenario.
The op wrote his post to state that in no situation would he do so. The scenario was for reasons not to, but he made a final mental determination to never engage except to save him or his family.
I understand that he may not have meant it that way but the op stated his and his only so the response by Constantine was a response to the am i wrong question.
Given what was clearly stated and asked it was a proper and justified response to the statement and the question that followed.