So far...as in Kirk has actually had the chance to play full-time this year and show what he's capable of. If someone told you at the beginning of the season that the Jays could get Soto on the condition that they include Kirk, I highly doubt you would oppose that. Moreno hasn't had that opportunity yet. Going into this year it's not like people thought of Kirk as they do now. Losing Kirk sucks, I'd rather they take Moreno but if the worst case scenario is they want Kirk, that's not something that would hold up the deal for me. The Jays have Jansen, Moreno and Kirk, moving on with two of the 3 is more than enough at the C position.
I also think you're understating the difference going from a Gurriel to a guy like Soto. I'd say it's more significant than whoever they would add to the infield after that. You have to realize that while moving Bo might hurt the depth of the lineup, it could also potentially improve the defence at SS with Espinal going there as Bo is no gold glover out there.
Furthermore, it would add more balance to the lineup as they Jays don't really have a power lefty bat, they're primarily righties.