(There are reasons for using "she" to describe Kil'jaeden. 1. All male Draenei have no horns, such as Archimonde and Velen. 2. All female Draenei have horns, such as Yrel and the Eredar Twins. 3. Kil'jaeden is an Eredar, but Kil'jaeden has horns. On top of that, Kil'jaeden and Velen grew up together and shared a deep bond. Yet after Velen left Kil'jaeden without saying goodbye, Kil'jaeden searched the entire universe for Velen for tens of thousands of years.
So... I have a very bold "guess.")
As the Archdruid's wife, Tyrande had no fondness for the Sunwell. Strictly speaking, both Tyrande and Malfurion rejected anything other than nature energy.
"We cannot let Kil'jaeden arrive. We need to return to Azeroth as soon as possible and eliminate the Burning Legion's threat. Azeroth is already riddled with wounds. Once Kil'jaeden successfully arrives, we will never be able to stop him from destroying Azeroth."
Everyone agreed with Tyrande, but Rhonin had plans of his own. Kil'jaeden's arrival was indeed a world-ending crisis, but a tremendous crisis also presented a tremendous opportunity.
Quel'Thalas had now made an enemy of the entire world. They only needed to unite the coalition forces of all Azeroth to conquer Quel'Thalas, then thoroughly purge Silvermoon City's leadership just as Arthas had done. After that, Dalaran could easily use the Silver Covenant and the Kirin Tor to inherit the High Elf Kingdom's legacy.
Once Quel'Thalas became Dalaran's territory, the former Dalaran survivors could slowly recuperate and rebuild in Eversong Woods. Elves reproduced slowly and could never overwhelm humans in population. As time passed, the Dalaran survivors would become the masters of Eversong Woods. Within ten or twenty years, Dalaran would become the world's most populous and powerful nation.
This may be why Modera specifically informed me of Kil'jaeden's impending arrival,