More unfounded Solas speculation based on scotch bonnet candies and Laidlaw's snippet that we can tick our companions off enough to make them leave. Inquisitor is pragmatic Dalish elf.
Solas: "Inquisitor, you cannot support Gaspard! It is a betrayal of our people. Do you want to see more generations of Elvhen children condemned to the slums, to servitude no better than slavery. Have you no conscience?!"
Inquisitor: "And would you prefer to see those Elvhen children die now, instead? Gaspard has the troops and the tactical advantage to end this now. And Celene is no better, she may speak of aiding the Elvhen, but she will do what serves her best."
Solas: "Celene has at least tried to aid our people. To Gaspard we have less status than the horse he rides. With Iron Bull's mercenaries we could bolster Celene's forces, and she already holds Val Royeaux."
Inquisitor: "Iron Bull's mercenaries are over a weeks march away. In that time thousands more will die if I don't get these rifts closed. To close them I need access to the city. If I wait, that blood is on my hands."
Solas: "And the blood of future generations will be on your hands if you don't. You have the gall to call Celene self-serving. Look in the mirror. For all you profess to support the Elvhen people, you only count the Dalish. I'm through. Goodbye, Inquisitor. I won't wish you good luck."
OR, if the Inquisitor has enough influence with Solas.
Solas: "And the blood of future generations may be on your hands if you do. Just remember, there are more Elvhen than the Dalish, don't forget that." walks away -10 approval