I don’t 100% agree with this as there is an entire sect to being wild, dirty, and surrounded by nature; The Farstriders.
I can see your apprehension at adding BE druids but I don’t see you raising objections of Worgen, Troll, Zandalari, or Kul’tiran druids. They’ve watered down and muddied the waters of druidism and stole the uniqueness of NE more than anything the blood elves could do.
If they wanted to just keep it simple they would just state the link of nature still connected to the blood elves was kept alive by a small sect of the Farstriders keeping the teachings of Ysera and the druids alive within their society. The gift of the link from Ysera was bestowed upon the Elves present at the Hyjal tree and some of them left with the Highborne.