Which is exactly why someone wouldn't just give away all their secrets, LOL.
Velocity can only affect flow when pressure is gone. Bleeding off more pressure wouldn't fix the inability to turn at that point and in fact make it worse - this is why I can't buy the velocity explanation.
I could see the crossover boosting volume (and thus increasing local pressure) at the #1 main, which could help prevent loss of pressure in the passenger galley to some extent by effectively "double feeding" the passenger galley, or at least a portion of it. Would work even better if it's easier to drill the backside of the passenger galley larger to help offset the outflow through the crossover.