The problem for you is that this statement does not conflict with Vatican II or with the "broader" interepretation of Extra ecclesiam nulla salus that has been around for centuries and was not invented at Vatican II. "Outside the church" can be further specified. The crytpo-Jansensist Feeneyite rigorists identify membership in the visible, formal Catholic Church with "the church" and to deny that anyone not a visible, formal member of the Catholic Church can be saved. Rigorism has been an issue for at least 19 centuries now--Novatianists were rigorists too (over different issues, but with a similar psychology).
Nor does the claim that one can be saved without being a formal member of the visible Catholic Church mean that one is being saved without Christ. Christ is active outside the boundaries of his visible Catholic Church. What the good Father Echert here asserts is that no one who is saved is saved apart from Christ.
What the 1949 Holy Office letter asserts (and a series of 19thc and earlier papal teachings also asserted) is that someone who is outside the visible Catholic Church because he knowingly and deliberately rejected her claims, knowing them to be true but still choosing to remain outside her membership, such a person is damned. But not all who are not formal adherents of the visible Catholic Church formed by those bishops in communion with the bishop of Rome and their flocks are damned. And many who are formal adherents and members of the visible Catholic Church formed by adherence to bishops who are in communion with the bishop of Rome, many of those could well end up in hell for sins against charity, sins against truth, for not living up to the higher obligations placed on them by their formal membership in that visible Church and their greater knowledge of the truths about the Church. Those who know these things and do not live according to them, those who violate caritas as in the 1949 letter, they are in deep doo-doo (as the letter did not say--at least not in those terms).
You silently inserted the word "visible" into Fr. Echert's statement, then invoked his authority for your rigorist position. That's sloppy reading and interpretation of the text.
That's true, but the Holy Office letter also teaches that those who are merely vincibly ignorant of the Catholic Church are also condemned as being "extra ecclesiam." An implicit desire can only exist in one who is truly invincibly ignorant, as the letter says.
"Extra ecclesiam nulla salus" is not a matter of a precept binding only those who know the Catholic Church is the Church of Christ and necessary for salvation; through this dogma we learn that formal membership in the Church is absolutely necessary by a hypothetical necessity of means (in re aut saltem in voto - it must be had at least in true implicit desire).
I would be interested if you could produce these "earlier papal teachings." As far as I can tell, the "rigorist" (i.e., something like this) reading of the doctrine was fairly common straight up through the 18th century at least, although it wasn't dogmatic.