This is the dilemma. What's the alternative? Let everyone else in the group know that there aren't any rules or prohibitions on killing people? They need to keep social order in that group, or there is a real problem. And Tyreese, assuming that he survives the trip to the hospital, doesn't seem like he's going to let this issue drop. And if Carol keeps running her mouth to more people, Tyreese is going to become a problem.
Very good observations and points. I’d hate to be in their shoes. I think Herschel is the most level headed.
It’s actually a very easy problem for Rick to solve. Let’s assume the worst case: she killed them while they were sick, and then burned the bodies (as opposed to them dying and then her burning the bodies). She was a caregiver. The story is — they both knew they were going to die, and were terrified that others would get the virus. Nearing death, they begged her to burn their bodies after they died to kill the virus. She honored their wishes, and did so. End of case, and Tyreese would have no real reason to be upset.
A little white lie and the issue goes away.