Yes, this is the basic principle that governs these discussions. Although this is a paraphrase of the specific teaching. The specific wording is: “it is necessary that each and every marriage act remain ordered per se to the procreation of human life.”
Some people interpret this one way or another, when procreation is already off the table. The word “remain” is one where some people disagree. Some say that the word “remain” makes the requirement only apply when procreation is possible, and that a marriage act that cannot possibly be procreative (when already pregnant, post hysterectomy, etc) carries no such requirement (ie to “remain” makes no sense). The teaching also includes this phrase: “man on his own initiative may not break” with regard to unitive and procreative aspects of sex. But what if it’s already broken?
So that’s where the disagreements arise. I’m not saying I agree with this, but that is the discussion. And I’m not saying it’s a commonly held view either.
And let’s look again at what Jimmy Akin said, as this link seems to be a catalyst for this discussion somewhat:
jimmyakin.com/2006/08/condoms_during_.html
Two key quotes I’ll point out:
“The Church has not directly addressed the matter that you have raised, so we must fall back on Catholic moral theology to try to answer the question. The answer below would be representative of what many orthodox Catholic moralists would say.”
This is essentially what I have been saying.
“it is necessary for some insemination to occur in order for the marital act to be completed”
This is an interesting interpretation of how the marriage act is defined. If it is correct then it would prohibit the use of non-perforated condoms even in sterile sex. But, as far as I know, this definition is not found specifically in Church teaching and is essentially derived from the principle addressed above.