I wasn't talking about the Catholic Church, I was talking about the Crusader Kings, they didn't know what they were doing and the Crusades only got as far as they did with luck. The Byzantines did know what to do and how to conquer in the Levant. It was really only the Byzantines with sensible tactics and diplomacy needed to succeed in the Crusades
Perhaps the Byzantines had a better knowledge of the region, but they lacked the military means to enforce it.
What he's saying is that such a reconciliation would incentivise the crusaders to aid the Byzantines. What reason do they really have to help them aside from that aside from those created by our modern hindsight such as the macroeconomic and political? If they reconcile then the crusaders could be more willing to actually help but aside from that they have no reason to go out of their way to help 'heretics'.
This, it should be the Byzantines, which have a very good offer for the Catholic Crusaders, they are in need of help, not the other way around, that's very basic Realpolitik. IMHO for that to happen both sides need to jump over their own shadow, both Orthodox and Catholics had pretty bad views from one another.
Add to that a 'Byzantine' Empire, which had to 'beg' for help in the 'Barbaric' Catholic west.
IMHO yes the Crusaders made mistakes, but Constantinople treated help from the West rather poorly. Let's just say, both sides had different expectations, and that gap was never breached.