Whilst I agree that the Scions should be called out for resorting to increasingly brutal measures to achieve their goals it's understandable as to why they would seek to liberate Doma and Ala Mhigo.
Still, by all accounts drowning is one of the most terrifying and brutal ways to perish - that they showed no hesitation once such a plan was suggested shows that they are more than willing to dehumanise the Garleans and those that serve them. Something which, ironically, they criticise the Garleans and their allies for doing to them. I would very much like to see the Scions either take a step back or become a truly neutral organisation instead of operating primarily in Eorzea's interests though. I would also very much like the opportunity to align with the more reasonable elements of Garlemald and work on a more diplomatic and peaceful approach.
Still, the 'terrorist' label is an interesting choice in words. Not entirely without merit, I feel - one man's 'freedom fighter' is another man's 'terrorist' and the lyrics of Revolutions certainly attests to their being two sides in every war. Whether or not we see consequences for the more horrific actions of both sides remains to be seen, though. I certainly hope so because one sided stories are far from 'Final Fantasy' and tend to be very dull. Especially when there's plenty of people rooting for the antagonists in each title.
Still, I'll reserve my judgement for future patches to see if the Scions realise that Zenos was not working for Garlemald, further conflict will result in an immense amount of bloodshed and that there's the Garlean Consulate in Kugane where an attempt at diplomacy can be made. If nothing else the Scions need to learn that a more nuanced approach is required - and that backing a faction as powerful as Garlemald into a corner is not a good idea. Though being able to do that in the first place would be questionable and I would much prefer a resolution similar to how Archades was handled back in FFXII or even the Shinra Corporation back in FFVII.