Yes. That's exactly how it is.
The Ren'dorei love Quel'Thalas. What they don't love is the Horde. They will never stop in their quest to free Quel'Thalas from the Horde and bring it back into the Alliance.
The Ren'dorei are like a group of Americans who would be mad if the USA suddenly joined the Axis, and worked to bring them back into the Allies side.
- - - Updated - - -
The Ren'dorei have unparalleled potential, they always had, I've been saying this since their introduction. It's up to Blizzard to fullfill that potential, or continue to neglect them, while focusing on the same 2 races that have been in the spotlight for 20 years.
Alleria Windrunner, the first of the Ren'dorei, the first mortal in the Cosmos to defy the Shadows' whispers, she is in a unique position in the lore. She works alongside Turalyon to mend the wounds of the Alliance, she continues to contend with the whispers, and simultaneously she seeks to bring Quel'Thalas back into the fold.
Magister Umbric, the original leader of the scholars who searched the Void, he has a unique character trait that not even Alleria has. He despises any kind of government that builds lavish riches at the expense of the common people, which led him into conflict with Gallywix, the former leader of the goblin who built his riches on the back of his oppressed people. He also seeks to prove the worth of the Ren'dorei to the Alliance, no matter the price. He can be ruthless and methodical in his approach, like when he and his followers meddled with the bones of the Zandalari dinosaurs in Zuldazar, to terrify the enemies. To prove the worth of the Ren'dorei to the Alliance.
The Ren'dorei are overall in a very unique position, they have always been. They represent a somewhat "darker" side of the Alliance. They are not evil, but pragmatic, in a faction full of Lawful Stupid idiots. They can be ruthless and conniving if the situation demands it. They do not shy away from employing shady tactics, if it can further their goals.
Like that time in the book where Alleria messed with the brain of a prisoner, to find valuable intel on Sylvanas' whereabouts. Was it a grim/unpleasant action to do? Yes. Was it justified/necessary? Also Yes. This is what the Alliance needs. People who are not afraid to get their hands dirty for the cause. It is therefore not a surprise that the Ren'dorei have a flawless record of successes since they joined the Alliance.
But now for the first time in years, the Ren'dorei are truly catapulted in the position to attain the spotlight. They can truly attain the spotlight. With Alleria Windrunner standing in the War Room, next to the Throne Room of Stormwind, while her husband Turalyon is de-facto regent of the entire Alliance. The Ren'dorei always had the most potential, but now they are truly in the position to get the spotlight, once FillerLands is over.