And again why? There’s plenty of Alliance and Kul-Tirans to go after. She’s got no special beef or relation with Sylvannas. She killed Lane because she was made to do so. the entire plan was to have her infiltratre Alliance ranks to make that happen.
There’s no evidence that Sylvannas did anything in particular to sour her Cherrios.
You know since Blizzard isn’t above repeating stories what if we learn that Cho’gall taught someone spell to control Garona. The Horde would then have a quest to save her, which would help confirm that she’s sticking with the Horde for the long run.
Alternatively she’s going to have an awkward scene with Anduin, where he forgives for killing his grandfather on account on being not in control of her actions and stuff. I don’t think this is likely but I can’t dismiss it.
Because she’s Azeroth’s best assassin.
I might buy into that idea more if the Uncrowned didn’t feel like they’re trying super hard in general to over inflate their importance and impact on history. Tethys works with the uncrowned, sure, but that doesn’t make the bloodsail automatically the most influential pirates everywhere.