I say, stay-at-homers can call themselves feminists, depending on the spirit with which they do it.

Not so feminist: "I choose a traditional role for women and I think that's the only morally right thing, and besides, men make more money so why shouldn't I? It's my choice, and [cliche cliche cliche] feminism's all about choices, right?"

More feminist: "I am choosing to be a stay-at-home partner because that's the life I want. I know it's a potentially temporary economic privilege, I know that I will be economically more vulnerable if my husband dies or if we divorce. However, despite the fact that I don't earn income, I assert myself as an equal partner in my marriage, asserting that homemaking has a value commensurate with paid work, and furthermore I don't let my husband call women bitches like that LW's fiance."

Feminism itself has room for almost all women who are sincere and thoughtful about the rights and welfare of women, as individuals AND as a group.