I have to concur with you, Sniffles.
As for McGonagall, she is certainly by-the-book.
Here's one that piqued me: When Harry used Snape's spell on Draco in The Half Blood Prince, Snape had him.
I mean, he *had* him. He had him red handed, literally. Harry had just used a Dark Spell on a fellow student, a sure fire reason for Expulsion.
Snape did not get his book back, because Harry hid it, but he still had the evidence to have Harry expelled.
Why didn't Snape pounce, after all those years of trying?