It was, and Robert Justman afterwards used to hide it in his office in various stages of undress to scare visitors.
Maybe it was the rush of episodic Tv in those days, but everything about the teaser was a misfire---the cold suits that are very ambiguous, the manaquin, Tomorlen's removing the glove and putting on the dead guys head, the odd way the virus gets on his hand.
Add to that everything Tomorlen does is weird---he knows he removed his glove and as soon as Spock said what he did about contamination--he should have said,"Oops, I removed my glove." Episode over.
Then after acting cavalier about the dead guy he seems so distraught about leaving "people to die on freezing planets."
Then Spock says his profile shows a lot of self-doubt and McCoy later says, "that man isn't the kind to give up."
Even as a kid I thought, "but according to what Spock just said---he's EXACTLY the kind of guy to give up!"
They clearly state that the virus brings out peoples inner true feelings and Tomorlen gets suicidal as soon as the virus kicks in and McCoy says it's not in his nature after Spock says it is.
I wonder if they just didn't want to acknowledge what was pretty clear---he had a predisposition for deep depression and suicide.
Maybe they didn't want to show that was still common in the future?