I don't understand you. The rest of the paragraph seems to be arguing that this was irresponsible idiotic behavior on her part; this sentence seems to be saying it's a point in her favor.

I approve of fighting bullying. I don't approve of initiating conflict when Harry saves their lives by pulling a Harry. Because his actions in that situation aren't really any of her business. Harry's actions in that scene are in acordance with Harry's Harriness and he would have done them without her involvement. They aren't about her (making this situation different in nature to the earlier incident pretending to be a ghost to stop a gossip.)

I think you're significantly misremembering what she said -- she explicitly didn't mind Harry saving them, she minded that he scared the bejeezus out of her.

Citation needed. Actually for realz, not as the typical 'nerd comeback'. I want to know what chapter to start reading to review the incident. Both because that is one of the most awesome things Harry has done and because I do actually recall Hermione engaging in behavior in the aftermath of the incident that makes me think less of her.

Most significantly she makes Harry give an oath that makes me think less of Harry (and MoR) for submitting to. Because he made a promise the adherence to which could make him lose the fight for the universe! I've actually had a discussion with Eliezer on the subject and was somewhat relieved when he admitted that he wrote in the necessary clauses but omitted them only for stylistic reasons.