Not that I get to sit in F, but...

No, I wouldn't "protect" the passenger. I'm firmly in the MYOB camp... unless the passenger specifically asked to be "protected" (or, conversely, to be woken), I'd just shut up and pretend the other pax isn't even there.

Good intentions are great, but it's not really anyone's business to act on behalf of another who has not requested such (except in grave situations, which this certainly is not).