I don't think freezing is anything to do with the nature of the assault in itself (sexual or non-sexual).
In a lot of self-defense literature, it's indicated that the nature of the assault WILL often dictate fight vs flight vs freeze. This is not looking at sexual assaults, only non-sexual "violent assault." Marc MacYoung (i think is his name) discusses this a bit.
One of the things posited is that the "freeze" response is often triggered/exacerbated/lenghtened because we, as an entire race of humanity, are not accustomed to letting the "lizard brain" kick in as often as we were when regularly threatened by (non-human) predators. We spend longer in freeze-mode while giving up control to the lizard brain necessary for survival. It's been posited this delay in "switching gears" may be related to the "blackout" that so many experience (rather than pure psychological dissociation)
My experience of fight/flight/freeze is that they're overwhelming and there's no conscious choice at all.
Absolutely! It just seems like the lizard brain may be a bit more sophisticated and astute in decoding threats than we generally give it credit for...
ROCK ON LIZARD BRAIN!