A Challenge for Clarification to Dr. Tollefsen

Today, on The Public Discourse (a blog I admire), Christopher Tollefsen discusses Pope Francis's presser comments on contraception and the Zika virus. This is a topic much in the news since the comment was made. Tollefsen is an author and professor of philosophy, who wrote a book called, "Lying and Christian Ethics." His reasoning is usually clear, and meaning, precise.

With that said, I would like to take issue with something he argues in this particular piece. Tollefsen makes a side-argument concerning use of contraception in the event of a sexual assault. As far as I can tell, this is Tollefsen's reasoning:

1. Someone being attacked may be attacked solely by bodily contact (a punch), or via longer-effecting means (a bullet lodged due to a firearm).
2. An individual being attacked has the right to defend herself, whether through opposing force, or by having the offending bullet (for example) removed.
3. Unwanted sperm in the body due to a sexual attack constitute a continuing attack - they are there not as a result of "one flesh union" but as an invasion.
4. Therefore, following the principal of double effect, the woman may take steps to prevent pregnancy - in his words: "rape victims can, and should, intend only the repelling or destruction of sperm, or the suppression of ovulation, as a means of defense."

Now, assuming this is accurate, it would seem to either have implications far beyond rape, or it creates a new philosophical definition of rape which ceases to have any relationship to consent. Here's my thinking:

1. In his "Theology of the Body," audience of 27 October 1982 John Paul II states that the words of Paul in Ephesians 5 "have a significance for marriage in which man and woman unite so that the two become 'one flesh,' according to the expression of Genesis (2:24)."
2. Therefore, and according to most of the other literature available on Theology of the Body, the idea of "one flesh" is committed to those in marital union. There is no "one flesh" union outside of marriage.
3.  If this is the case, does every instance of intercourse outside of marriage constitute rape?

Therefore, if all non-one-flesh intercourse is rape, are all women who have extramarital unions (consensual or not) permitted to use methods to stop the sperm?

Other questions Mr. Tollefsen's article poses:

1. When does consent change the nature of the continuing attack? And can it be revoked? Let's say a man attempts to seduce his wife, but she rejects him. He waits until she has a couple glasses of scotch, falls asleep, and then has sex with her. Does that constitute lack of consent, and is the woman justified in using sperm-destructive or anti-ovulative methods to stop his sperm?
2. Say the woman is upset about what he did, does not use these sperm-destructive, etc. methods, and later finds out she is pregnant. Has this ceased to be a continuing attack? Why or why not?

Let's pose a slightly different scenario: suppose the wife drugs the husband or gets him drunk when he was unwilling, and then forces sex with him while he is drunk. Is he later justified in forcing her to kill his sperm? Why or why not?

UPDATE / CLARIFICATION OF MY OWN:

A Twitterer asks me why I ask, as it seems to him that Tollefsen explicitly limits the double-effect use of sperm destruction / non-ovulation ("SDNO"?) to "violent non-conjugal acts." Tollefsen does make explicit the foundation of his reasoning in the violent act of rape. Moreover, he notes:

This form of invasion is unique, for it comes to fruition as an invasion in the same event that sexual intercourse comes to fruition as a one flesh union, namely, the penetration of the ovum by a sperm.

He seems to make a distinction here between "invasion" and "one flesh union." As noted above, one flesh union is a reference to the act of consensual intercourse within marriage. Presumably, invasion he would define as as "the act of ejaculation in side the woman during sexual intercourse accomplished through violent means."

My concern here is whether "violent" and "non-consensual" are always congruent in this reasoning. Is sex between one drunk (therefore, impaired consent) and one sober individual violent? And following, whether non-consensual, though marital, intercourse also qualifies for this principle?