The more I mull on this, the more I come to the conclusion I did while reading: Tris has always used the enemy's tactics, even when it wasn't good and she called it cruelty and a fault of hers. She can be vengeful, unforgiving, and when unable to figure out a better plan has resorted to shooting, killing, etc., sometimes cruelly. Like Four, she has to struggle with kindness. It's not really in her nature.

So I think that's why I saw the hypocrisy, the compromise as you put it, but it didn't surprise me. Nor did it surprise me that Four saw the hypocrisy, didn't like it, and made a different choice when faced with his mother. In book one, he was yanking Tris back and discouraging her giving in to her crueler impulses.

So I think that's why I went with it, even though I did think it was wrong of her.