I would like to understand this passage in Makkot 7a:
[The mishna teaches that] Rabbi Tarfon and Rabbi Akiva say: If we had been [members of the Sanhedrin, we would have conducted the trials in a manner where no person would have ever been executed. The Gemara asks:] How would they have acted [to spare the accused from execution if witnesses testified that he intentionally committed murder?] Rabbi Yoḥanan and Rabbi Elazar both say [that they would have asked the witnesses]: Did you see [whether the accused] killed a tereifa, [i.e., a person with a condition that would lead to his death within twelve months,] or if [he killed someone who was] intact? [The halakhic status of a tereifa is like that of one who is dead, in the sense that one who kills him is not executed. Since no witness can be certain with regard to the victim’s physical condition, they would invalidate any testimony to a murder.]
Surely it does not mean it is acceptable to kill a terminally ill person, does it?