If there are men who are protecting women, the possible perpetrators that they are protecting against are irrelevant. If I protect my wife and lose my life as a consequence, then I sacrificed my life for her safety. The fact that another man was responsible for killing me does not make my sacrifice any the lesser.

I agree, if we shouldn't assign collective guilt to men, then we shouldn't give them collective credit either. Some men are protectors, others are not. So I agree, "not all men" is applicable for good stuff as well as bad stuff. Additionally, men are not obligated to protect women, simply because their gender any more than women are obligated to “make men a sandwich”. "From other men" part is irrelevant, period.

If I were a fairer minded person, the "not all men" refrain would have come from me regardless of whether the generalization was disparaging men or giving them unearned credit.