Some of those lines were taken directly from TW1, but yeah, his entire character is a missed opportunity: not only does he share common history with both Ciri and Geralt, he also has clear motivations for his actions that the game never even tries to get deeper into nor expand upon. Surely you should be able to at least initiate dialogue with him, right?
TW3's narrative in general feels rather inconsistent when looking at different parts, areas and characters in the game. You've got Velen, where every notable character is flawed and tormented in some way, and from there you jump straight into Novigrad where bad guys are super bad, good guys are super good, and only a few characters (most notably Dijkstra) fall somewhere in between. In many places the game (like the books and the previous games) consciously avoids or subverts medieval fantasy clichés, but in the end the main quest pretty much embraces them and decides to solve things by having an epic battle or two. The Wild Hunt itself is a mash-up of different ideas and interpretations that doesn't work particularly well on any level. There's a bunch of minor inconsistencies that appear throughout the game, which are insignificant on their own but might be symptoms of a bigger issue. For instance, in one part of the game Geralt tells people to draw a line of salt at their doorsteps to keep ghosts at bay, yet later on in another quest he dismisses the same thing as pointless superstition. It feels like all of the writers weren't quite on the same page about the themes and how the world was supposed to work, that the game was written by several different writing teams but there was no strong-willed director to keep it all in check. To an extent you can understand it given the size of the game, but there's really no excuse for the main story of all things being such a mess.
