Then I would hope that Solas wouldn't be coy in not telling the Inquisitor.
IF the man's cause is just, then there is no reason that "heroes" would not align with it.
I have had no indication that he has even so much as tried to question whether or not the Veil could - for example - be let down slowly, with all the world in agreement to the purpose. Is it a foolish thing to consider? Perhaps - perhaps not.
After all - does not Solas claim that the world without the Veil is superior? Would not - with some irrefutable examples - the leaders of the world not agree to this superior world?
... And how many years WE ourselves spent to come to accept that the world we have now - with no institutionalized discrimination, separation of church and state, free access to information, and no rulers or religious institutions fiercely protecting the established status quo to the point of absurdity - is superior to what we had before?
I mean... wasn't there a bloody Civil War in America to abolish slavery??? Because half of the country was unconvinced that freedom for everyone is actually better for everyone? How many years did we have to fight for equality on many levels? And there are still some that are unconvinced that this is better :/
So how do you expect the world; with the South mostly shaped by Chantry rhetoric that deems everything behind the Veil as dangerous, or Qunari who actually are working to strengthen the Veil, to just accept the Veillless world and everything that comes with it? In a perfect world where everyone was rational and logical this could proooobably be accomplished. But we know Thedas isn't such world - it's ruled by biases, emotions, close-mindedness and conformism, similarly to ours. So it's naive to suggest that Solas would just be able to approach leaders of the world, provide "irrefutable examples" and everybody would be just like "okay, so is 5 o'clock tomorrow the best time to tear that pesky Veil"?
....Heck, even though Inquisition has vastly improved the state of South, no matter of it's leader's quality, Ferelden and Orlais still want to either dismantle or absorb it, seeing it as a threat, rather than a force to build upon in order to help the South become better for everyone. Celene wanted to slowly, but steadily improve the situation of the elves, only for her political rival to use it against her and had thrown Orlais into devastating civil war. Andraste stood against slavery imposed by Tevinter, only to jump-start a cult that supports existence of society where entire groups of people are discriminated or subjugated.
And hey - who knows; perhaps Solas do indeed wants to show people that the world could be better without the Veil or simply different than it is now? But perhaps he knows that he can't just do it the simple way? After all, the South began pulling itself form the edge of the abyss and actually working towards greater goal only in face of a giant, unknown threat. And no, I'm not saying that Solas is just orchestrating a fake threat to make everyone work together. But the truth is we don't really know what he wants to accomplish.