It means enough, to say how invested Paarthurnax was in that side of the battle. She guesses it is hard to choose another side over family. It isn't just her.

"I don't think it is. Or at least, it shouldn't be." She's not thinking of her father now, but her uncle. Had it been easy to betray him like she had? No, but it hadn't been as hard as it should have been, either.