Patrick knew that his sister-in-law was not only deeply responsible but even more curious. After Sylvanas keenly discovered the presence of those traitors, she felt certain there was more to the story and resolutely decided to follow Arthas's forces in secret to uncover the truth.
Sylvanas's actions disrupted Patrick's original plan. He had actually wanted to use Arthas to purge the cancers of Quel'Thalas's society, allowing Quel'Thalas to rise from the ashes like a phoenix.
Now he had no choice but to set the Floating City in motion ahead of schedule and head toward Silvermoon City. Goldenmist Village in the Ghostlands had already been destroyed during the Second War, and no elves lived there anymore. Only the people of Suncrown Village still lived in their original homes, but with the outposts Patrick and Alleria had established in Life Forest, along with the harbor Suncrown Village had built on Lake Elrendar, escaping Arthas's butcher's blade would certainly be no problem.
(A note here: the spirits of elves still lingered in the former Goldenmist Village, which suggests that Arthas probably was not the one who killed those residents. Had the undead done it, there probably would not have been a single corpse left. Souls and bodies alike would have been controlled by Frostmourne and joined the undead army. Suncrown Village, for example, had only spider creatures left in its ruins. So the setting has been adjusted here.)
Patrick had been laying the groundwork for dealing with the undead all along. Even his earliest plans for the herb-growing camps in Life Forest had been intended for this purpose, as had the food, military supplies, and materials mindlessly stockpiled in the Floating City for decades. All of it had been preparation for the aftermath of the war.
In his previous life, after Silvermoon City