I mean, that's arguing from a point of clear omniscience. If you are making a moral argument, you really need to argue from the character POV, not from the omniscient narrator's.
And when you look at it, Jaina acted on the following knowledge:
- At least one Sunreaver was explicitly involved, but she does not know how many more. At that point, it is only known that the Sunreavers are involved, not who precisely.
- Aethas said that "he did nothing", not even denying his faction's involvement, just that he himself did nothing or did not order it. Jaina has no way of knowing whether or not he is lying and/or even in full control of the Sunreavers.
- Jaina has no idea just how many Sunreavers are actually still neutral and how many are secretly or overtly working for Garrosh, just that at least some of them are.
I still think Jaina jumped to conclusions in this in general and acted too brashly. However, I also find it disingenuous to frame that has 'punishing all for the action of one'. We don't know if she would have done that one. We only know that she knew that members of the faction betrayed her and that she decided to imprison them all to send them back to the Horde, but show no mercy to those who resist. You can criticize how she did it, certainly, but do not misrepresent the motivation.
Those aren't great examples, really. The Alliance as a whole decidedly disagreed with Jaina's plan in Tides of War (she only went with that flooding action because the Alliance would not commit to go all destructive on Org) and even then she eventually allowed herself to be talked down. Both Daelin and Garithos were never members of the current Alliance to begin with. Garithos was a relatively low-ranking officer being catapulted in charge of Lordaeron's remaining forces and not acting under Stormwind. Daelin was Kul Tiran hunting down the orcs that just violently escaped their camps and who were building a new base of power in Kalimdor. I admittedly do not know much about what happened with the Goblins, but again the Alliance probably did not even know that these ships were full of goblin refugees to begin with, just 'goblin ships' in general. So they couldn't have possibly been trying to 'destroy a kingdom'.
None of those really match up to the act you are trying to compare it to since they do not just differ in successfulness, but also in just who does it (non-Stormwind Alliance members vs Horde's explicit warchief, people going against explicit Alliance orders and interests) and motivation (not trying to destroy a kingdom). Hence, bad comparison.