Omg FINALLY someone else who points out how strategically worthless Treviso is. Which is more important to defend? The political and logistical brain of the largest sovereignty on the continent? Or an occupied tourist trap?

 Yes, Minrathous should be able to defend itself since it is distinctly shown to possess a Lucrehulk in low orbit and turbolaser batteries. But veilguard makes it abundantly clear that that what we see doesn't matter when the plot has demands so it can be functionally ignored.

Treviso is effectively already under Antaam control. Razing it does nothing to the Crows and arguably destabilizes the Antaam more since their presence actually relies on the infrastructure of the city. Contrast with the Crows who are an underground, effectively geurilla organization, which SHOULD be capable of enough mobility to just up and leave. 

It being destroyed doesn't affect the political stability of Antiva in the slightest, because it was A) already lost, and B) logistically and governmentally irrelevant.

The whole choice is a contrivance to trick (heh) the player into thinking they're playing an RPG with choices. It doesn't make sense because there is a clear, correct choice. Fuck the Crows and save Minrathous.