I suspect that most of the "feminists" who defend male-only Selective Service (or shrug their shoulders at it) are breathing in a sadistic odor of "turnabout is fair play" in seeing members of the opposite sex indiscriminately turned into cannon fodder.
Unless, of course, it ends up being their own sons/husbands/brothers/uncles/nephews. Oh, THEN it's suddenly different...
Of course, I have my doubts that a majority of ACTUAL feminists seriously/literally support the continuation of the Selective Service status quo.