mehavey, note the bold, italicized,
and capitalized word in my first post.
IF it's found that he used too much force to hold her, he's on the hook for her death. It's no defense to say that he didn't know she was especially fragile; that's the point of the eggshell skull doctrine.
Of course,
IF it's found that the level of force he used was reasonable under the circumstances, then the consequences of using that force don't fall on him.
The legal vulnerability arises if someone says, "Well, yeah, but he didn't have to
hold her down, he coulda just..." -- and the jury agrees that he used more force than was reasonable under the circumstances. If they decide he used more force than he should have, he'll be on the hook for the consequences of using that force, which include her unexpected death.
pax