I personally am glad they made it a choice because I HATE it when a character hides something like that for no good reason. If movies have taught me anything, this only ends with tragedy. This way, people can choose not only the why but the reasoning why.
I chose to show because other than hating that trope of hiding a fatal wound, I couldn't think of a good reason to lie. My Lee had been totally honest in just about everything, so I figured he should be honest here. It may panic some people for a little, but it could be a lot worse for them to learn later. Plus, it is a good way to genuinely earn sympathy for finding Clem (though Kenny is at first in shocked denial only to then try and say how I've not been there for him).