You got that right. All of the hallmarks of infallibility are present in the documents that you mentioned. As you said, Ordinatio Sacerdotalis was a crystal clear example of infallibility and yet certain groups still refuse to acknowledge it as definitive. A clear look at the text of the infallible part of Ordinatio Sacerdotalis and the text of the decrees of Vatican I and Vatican II on how to determine when the Church teaches infallibly make it abundantly clear that the Pope intended this statement to be an infallible exercise of his teaching authority. The Dogmatic Constitution of the Second Vatican Council, Lumen Gentium, clearly decreed this concerning infallibility of the Pope :
“And this is the infallibility which the Roman Pontiff, the head of the college of bishops, enjoys in virtue of his office, when, as the supreme shepherd and teacher of all the faithful, who confirms his brethren in their faith, by a definitive act he proclaims a doctrine of faith or morals”
Now when we compare the above statement of infallibility to the actual text of Ordinatio Sacerdotalis:
Wherefore, in order that all doubt may be removed regarding a matter of great importance, a matter which pertains to the Church's divine constitution itself, in virtue of my ministry of confirming the brethren (cf. Lk 22:32) I declare that the Church has no authority whatsoever to confer priestly ordination on women and that this judgment is to be definitively held by all the Church's faithful.
All of the criteria set out by the above passage of Lumen Gentium for papal infallibility are clearly met by Ordinatio Sacerdotalis. The pope proclaimed, by a definitive act, a matter of faith and morals, to be held by the whole Church, and by citing his ministry to confirm the brethren, the pope has clearly invoked the power of infallibility, because Lumen Gentium declares explicitly that the power of infallibility protects the pope when he is confirming the Brethren in the faith by a definitive act. (The definition of Papal infallibility from Vatican I's Pastor Aeternus also could be used to demonstrate the infallible nature of this statement.)
The CDF said that the above statement from Ordinatio Sacerdotalis was infallible because of the Ordinary and Universal Magisterium but that it was not a solemn definition in itself. That seems a very odd statement, because isn't a definitive act a solemn definition by definition? Doesn't the fact that Ordinatio Sacerdotalis issued a solemn definition to be held by the whole Church make it in and of itself, a dogmatic definition? Wouldn't that then constitute a textbook use of the Extraordinary papal magisterium rather than the Ordinary and Universal papal Magisterium? The only thing it seems to be missing might be an explicit anathema upon those who refuse to assent to the definition. However, I suppose that it could be argued that an anathema is implicit against those who refuse to assent to the definitive acts of the magisterium. After all, presumably those who refuse to assent to the Church's definitive acts are outside Her aren't they?
I think the CDF was trying to get across the idea that infallibility rests, basically, on the degree of definitiveness announced in the text of a particular pronouncement, not in some specific set of words.
I assume that “solemn” refers to the sort of thing that was done in 1854 and 1950 and the CDF was trying to wean people away from the idea that the Pope has only spoken ex cathedra and infallibly twice in the last 200 years.
But beyond that, I too am a bit mystified by the distinction being drawn in the response to the dubium.