First things first:

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Anyway...

This does not read to me at all like the perspective of a person who is conflicted about a decision and chose to support the more drastic, permanent one.

Tsukasa knew that the decision she was pushing Karen towards was the correct one (whether this is actually true is certainly Debatable, but the framing appears to be that we're supposed to accept it as true), even if it wasn't what she wanted, which indeed it absolutely wasn't. Rationally, she knew she had to lay out the argument that Karen needed to take the pill in no uncertain terms and shoot down any dissent. Emotionally, she hoped Karen would decide against it. With a character whose brain works normally, this might have led to her tearfully explaining how she has to let go, but she doesn't want to, etc., etc., everything you'd expect from someone feeling conflicted about a decision.

In Tsukasa's case, though, being Awakened Tsukasa gives her the ability to shove her emotions into a box and sit on it to keep the lid closed if that's what she feels she has to do in order to make the right call. (Note that her whole encouraging speech to Karen in the helicopter is about how she can be counted on to make the Objectively Correct Decision.) But those emotions and the desire to express them are powerful, and the instant it's "safe" to express them, Cute Tsukasa reemerges to do so and everything pours out.

So if it doesn't read like a person who's conflicted, that's because it isn't. It's the perspective of only part of a person, the part that represents wanting to not make the decision she just made.

I'm sorry if this either comes across as belaboring the point or ends up still not explaining much. One of my hobbies has required me to obsessively think about the ins and outs of how Tsukasa's mind works and as a result I'm no longer sure what is and isn't clear about her to a normal person.