Why would Odo bring greater compassion to the Great Link? He's not particularly compassionate. He's not really much different from the rest of the changelings, in fact. He seeks "justice", which isn't much different from the changeling-wide desire for order, in fact, it's pretty much the same thing. Odo wants "Justice", but only justice that he sees as such. If there's any exchange of views, it would be that Odo would end up being overwhelmed by the Great Link's view of Solids. It is far more likely that Odo would come around to their way of thinking, rather than bringing them to his way.
I don't think Odo would make Changeling society more compassionate, but his knowledge of the Federation would convince them that they will not
try to destroy or enslave them, and that at least some in the Federation are caring and respectful toward changelings who aren't trying to enslave them.
"The Federation has many flaws but a desire for conquest is not one of them", he convinced the female changeling of that and I think he then convinced the rest of the link. And Odo believes in strict order, but he's also very anti-expansionist and believes in the right of the harmless to be left alone. I don't think he'll convince the rest of the link of that, but it might wear down their idea that any solid they don't directly control is going to come murder them.
There is also the fact that after the Founders tried to enslave their entire quadrant and murdered billions, the Federation made no attempt to prevent Odo from delivering the cure back to the Founders, which probably gave the Founders tremendous reason not to fear a revenge strike if they leave the AQ alone.