I googled the Hillel quote, and I see what you mean. Most online sources seem to be fairly consistently, "who will be for me?" This may actually be it. I don't know Hebrew, but I do know that two people can translate the same statement in slightly varying ways. But I don't see that it changes the meaning all that much.

It's pretty similar to Jesus' "Love thy neighbor as thyself." Which is to say, "If I don't love myself, who will? But if I love only myself, what sort of creature am I?" (Ominous question.)

Don Firth