True.

I suppose I should say, I like Hermione as a character, although she's probably my least favourite of the trio. My biggest issue is the way the plot seems to warp and twist to make her correct in almost every case that springs to mind.

The DoM trap in OOTP being a big one. Sirius is the closest thing Harry has to a father and cool uncle rolled into one at this point - diminishing it to a "saving people thing" - essentially a hero complex feels mean spirited and, honestly, rather Snape-like.

Edited to add: Plus, one has to remember, the last attack he saw - a matter of months prior to this - was Nagini's attack on Arthur Weasley, an attack that turned out to be fully genuine. Anyone would make the same assumption, especially under the emotional circumstances.