The Guardians of Hyjal is a neutral organization. Pretty much a branch of the Cenarion Circle. They wouldn’t turn away refugees in need of a home.
Even the tauren members are likely to accept the night elves with open arms and let them settle there. As Amadis points out we see night elf and tauren druids still working together during the Heart of Azeroth quest chain.
Only issue I see is that the Well is particularly dangerous right now, but we team up with Aviana to quell it so maybe that issue is resolved.