Every single interaction in this series since they mentioned a gift stealer has been stupid. The fact that in his last life he knew there was a huge threat but that they can be sealed and not murdered is dumb. Clearly they had the ability or could have subjugated after the seal before anything else
to be fair, it was explicitly mentioned a few chapters ago, that he wouldn't steal that musclebound halfwit's berserker since it'd absolutely throw everything he has, everything he spent 200+ years collecting, all his efforts, his ambitions, down the drain in one fell swoop. So as much shit we (rightfully) give this story, this one was properly foreshadowed not that long ago (the way it happened on the other hand is completely bullshit, but I digress)