The judgment of Exile, when “My people” became “Not my people” is undone when God acts to restore Israel to the Land. Paul, in Romans 9:25-29, quotes from Hosea to evoke God’s covenant faithfulness beyond the judgment of Exile. Paul could be evoking promise to the Gentiles (as his ministry shows) or he could be thinking of the fulfillment of reuniting the Twelve Tribes.
By bringing in Isaiah 10:22-23, Paul also evokes the hope of the remnant who will return.

God, Paul is saying, was in fact faithful to his promise: he remained present with Israel in what they thought was absence. He brought them up and back to the Land.
Wright connects Isa 10:22-23 with Isa 28:22 and the “stone” and the Messiah and then connects the Exile with the Messiah who bears the sins of the world. (For those who criticize Wright for not seeing some kind of imputation of our sin to Christ I don’t know if they have seen what he says here: all the sins of the world are funneled down to the representative Messiah — p. 643. Sure looks imputational to me.)