Prescott, I think, feels he scores a rhetorical point- one that Patel is happy to concede - that the Human Rights Act needs to go. Presumably he sees this as one of the key achievements of Labour's term in office. I don't know if he's right in what he alleges, namely that Parliament is powerless to resist the Strasbourg court, unless they abolish the HRA. He ought to note that no Parliament can bind its successor, as the saying goes.
It often seems the case that periferal issues, and I would say prisoners' voting rights is one such, lead to more important issues being dragged into the light, in this case Britain's subservient status in the European Union (yes, I know the ECHR is separate, that just makes the point even more so). Sometimes one thread can unravel the whole blanket. If this leads to Parliament reasserting its primacy against foreign princes and prelates, there will be cause for celebration, and if the HRA were to be repealed, a very welcome debate would ensue on what exactly our rights and liberties as individuals consist of. This, though, seems very unlikely at present.