https://wow.gamepedia.com/Quel%27Lithien_Lodge
The Wowpedia summary is pretty succinct on this lodge.
"The lodge fell on hard times following the Scourge invasion of Quel'Thalas. It was here that the banished rangers under Renthar Hawkspear took up residence after Grand Magister Rommath's return from Outland; Renthar and his group had dissented against Rommath's teachings on moral grounds. To avoid the nation becoming divided on the issue, as the teachings had been an essential boon to the elves, Lor'themar, now Quel'Thalas' regent, exiled the group south."
I want you to read that carefully. These Elves were banished to Quel'lithien AFTER Grand Magister Rommath returned from Outland with Illidan's teachings.
Yet when were the High Elves renamed as Blood Elves?
AFTER Kael'thas returned to Quel'thalas from Dalaran. So, Kael'thas gathered the survivors, renamed them Blood Elves and then headed south with an army to assist Garithos. Lor'themar Theron was left in charge of the Blood Elves.
The rangers who took up residence at Quel'lithien were only banished when they objected to Rommath's teachings. Rommath did not return until after the following had happened.
1.)Kael served with Garithos and the Alliance for a period of time.
2.) Kael was betrayed by Garithos.
3.) Kael and the Blood Elves escaped to Outland with the Naga
4.) Kael and the Blood Elves swore to serve Illidan.
5.) Kael and the Blood Elves accompanied Illidan to Icecrown.
6.) Kael and the Blood Elves fled back to Outland.
7.) Kael sent Rommath back to Silvermoon with Illidan's teachings.
8.) Lor'themar exiled those who refused to follow the new teachings on the grounds of national unity.
So the simplest explanation for the rangers of Quel'lithien is that they did in fact call themselves Blood Elves for a time, but Illidan's teachings disgusted them so much and they found their exile so embittering that once they were cast out they embraced the name to show their rejection of what they felt their people had become.
But for a time, yes, they would have been Blood Elves. And then they demonstrated just how profound a change that was by easily reverting to High Elf, proving at the end of the day it's just an adjective.
Void Elves will have a much harder time undoing their skin tone changes, tentacle growths and connection to the void let me assure you.