No, because we literally have everything you listed as a benefit from accepting them already, plus more.
1. Unity is not a problem for us. Our Joyous Symphony gives us strong unity as an inherent trait, and our people already dislike the nomads, to the point where for anyone else, we actually need a reason to attack them, but for the nomads, we have carte blanche to wage war whenever we want.
2. You can't get tech from tortured prisoners. First of all, the tech we need has to be taught over years, and there is no way the captured nomads would show us their secrets if they hate us. Secondly, our people don't know the extent of their training in horsemanship, so there is no way we will even get half as much tech from your plan as we would if we recruit them.
3. I'm sorry, but are you trying to turn us into a stereotypical evil empire? When advocating the use of hatred and torture as part of our national culture, well, you might want to rethink that plan...