[Firo hesitates; the fact that the queen lied to her people hadn't really registered with him until Prompto said it. That might be a big part of why he doesn't comment on it verbally, instead moving on to the other points.]

If it's so important for Astoria, she can come down here herself. [He sighs.] Besides, I get what you mean, but wouldn't helping their city get attacked be like abandoning the mermaids instead?

[Not that the mermen still chilling in the rift are exactly fearsome attackers...]