I believe that Ratzinger was deliberately trying to reabsorb the Traditional movement (using said Hegelian dialectic) just so he could infuse into it the Conciliar mentality, and therefore poison it.
He accomplished this, 100%. He introduced compromise, contradiction and confusion into the Trad movement, dividing the younger generations from the older, more knowledgeable generations. Look at all the neo-Trads (i.e. Xavier) who think they are Traditional but still accept V2 errors (i.e. watered-down EENS) and the new mass (i.e. directly or indirectly through the indult/"extraordinary form" lie). He appealed to the millennial generations's lack of historical knowledge, and their craving for novelty.
His motu which "freed the TLM" is a complete contradiction. While it is an (indirect) legal confirmation of Quo Primum, at the same time, it boldly ignores QP's regulations as if it doesn't exist. On the philosophical and moral fronts, the idea that you can have "two uses of the same rite" is as unorthodox and illogical as being validly married to 2 different people. There is no historical, doctrinal or theological basis for any of this.
When his efforts were torpedoed by Bishop Williamson's ɧơƖơcαųst comments, he was told by his handlers to step aside, because his main mission had failed.
Yes, he failed in only one of the specific goals - to ensnare the sspx into the vatican club. This was a short-term fail, because, as we've seen, the sspx was already prepared for such an agreement. In the long-term, they will eventually still be ensnared. They have already become an indult-community; it is only left to make it official.