A thought about Donnie Darko (kinda long -- spoilers)

*SPOILERS*

I saw this movie for the first time ever on Saturday, having never heard of it before. After watching it, I spent the rest of the weekend looking up explanations and analysis videos. It's an intriguing movie.

One thing I haven't seen discussed anywhere... Does anybody realize Donnie probably saved his little sister from Cunningham (Swayzee)?

Supporting evidence:
- Cunningham is caught with kiddie porn, so we know he's a sicko
- He's got some connection to the dance team Sparkle Motion because he greets them backstage before they perform.
- The dance coach, Kitty Farmer, is completely under his spell, even choosing to defend him after he's outed, rather than support her own daughter, much less Donnie's sister, on the dance team.
- During the song "Head Over Heels", Ms. Farmer at first seems to stare down the bully kid, but upon further watch, she can't take her eyes off him and seems to long for him, even choosing to follow him after he goes by. The words in the song at that exact moment are, "I wanted to be with you alone...". So, she may be battling some young lust herself, which she suppresses or hides through her moral crusading.
- Also during this song, Drew Barrymore looks disturbed when she sees the girls practicing their dance routine, as if they're being exploited in some fashion or another, and then you see her walking away looking pissed off.
- Donnie and Gretchen's class project was a device to shield children from dark or evil imagery, and they discussed what small children might or might not remember from their childhood experience while growing up.
- One point of "The Philosophy of Time Travel" is that people in the tangent universe may or may not remember some of their experience there after it collapses
- During the song "Mad World", you don't see the little girl wake up in contemplation like the others, because she probably has no memory of the tangent universe. That might not have been the case had Donnie not intervened in time.

There are a few other subtle things, but that's the crux of my argument. Anybody else pick up on this? Or am I reading entirely too much into this? Or was this completely obvious, and I shouldn't be patting myself on the back for realizing it?