Why did they kill Mr. Hengist in “Wolf in the Fold”?

In the season two episode of Star Trek, “Wolf in the Fold”, they discover that there is a non-corporeal entity that has been going around the galaxy committing murders for a very long time. During their investigation, they discover evidence to implicate the Argelian chief city administrator Mr. Hengist.

In the end, they transport him out into space to eventually die, but before they got him to the transporter room, the entity had jumped from person to person. It was simply by chance that it jumped back into Mr. Hengist before they caught it and transported it into space. Just a moment earlier, it was in the prefect Jaris, and before that, it was in Scotty several times.

It seems arbitrary that they chose to kill it instead of trying to contain it and try to find a way to extract it from Mr. Hengist.

This scene made me pretty mad because it was really selfish and callous. Would they have jumped to beaming Scotty out into space or bothered to try to extract it?

Did I miss something like that Mr. Hengist never existed and it was just the entity in disguise the whole time, or did they really just kill him without even trying to get it out?

star-trek star-trek-the-original-series

Best Answer

As this review by the A.V. Club says:

... this alien creature is called a Mellitus that can possess people and lives off of fear. It's been traveling the galaxy on a killing spree for centuries, and it landed on Argelius because everybody was so happy, and ripe for gutting.

and

Kirk figures out that Hengist has a connection to the entity, and when Hengist tries to escape, Kirk punches him out. He was dead all along, possessed by the creature...

Beaming Hengist into space was less of a moral problem, due to him being dead already.