Quote 1
"What has been proposed is that in lieu of eliminating the entire Capitol population, we have a final, symbolic Hunger Games, using the children directly related to those who held the most power." (26.47)
Coin's using the same tactics the other side did. It sounds at first like she's turning the tables on the Capitol, but really she's just imitating them. Wasn't this war fought to bring about change?
Quote 2
What's irrefutable is that she's done exactly what he said. Let the Capitol and the districts run one another into the ground and then sauntered in to take power. Even if that was her plan, it doesn't mean she dropped those parachutes. Victory was already in her grasp. Everything was in her grasp.
Except me. (26.4-5)
Coin's power is stronger than either truth Katniss is facing. No matter what chain of events unfolded, Coin is the one who benefited: the one who rose to the top. Coin is the only one who's come out ahead in this war. And whether the rebels or the Capitol masterminded this last unforgivable act, it still worked to Coin's advantage.
Quote 3
[Coin…] gives my eulogy. Praise for the girl who survived the Seam and the Hunger Games, then turned a country of slaves into an army of freedom fighters. "Dead or alive, Katniss Everdeen will remain the face of this rebellion. If ever you waver in your resolve, think of the Mockingjay, and in her you will find the strength you need to rid Panem of its oppressors." (21.28)
Admiration for Katniss is being used to further the rebels' cause. Katniss is being used like the Mockingjay, which she symbolizes for the rebels. Here Coin is speaking through her to support the rebellion. The greater Katniss's achievements, the more powerful she is as a symbol of martyrdom for the rebel cause.