On the first viewing of "Unnatural Selection" (TNG 2.7), are we supposed to believe Dr. Pulaski can really die?

One of the biggest difficulties of most episodic dramas, including the various Star Trek series, is that putting main characters in danger is seldom believable. It's such a common syndrome that it's even a pop culture trope: plot armor. Watching the early second-season episode "Unnatural Selection," in which Dr. Pulaski is infected with a rapid-aging syndrome, I wonder if the writers are counting on the viewers not believing Dr. Pulaski has plot armor.

After all, she is a recent addition and she is not even listed on the main credits, instead being designated as a "guest star." More fatally still, the episode supplies fresh background about the character and especially her desire to serve with Picard -- and every viewer of a reality TV show knows that once a contestant gets backstory and calls their family on camera, they're probably going home that episode. Perhaps they even expect viewers to remember that they did really kill a main character, Tasha Yar. Maybe this will just be the season of rotating-door Chief Medical Officers, much like season one had a different Chief Engineer every time it came up.

I'm especially interested to hear from people who remember watching it when it first aired, but everyone who watches an episode is watching it for the first time. Did you think Dr. Pulaski could really die?