No he didn’t. Metzen said nothing that means he rolled with it. Also Odyn mentions the First Ones too. It is canon even if we may or may not hate it.
This is actually the perfect way to describe this.
Manga WoW and Anime WoW have completely different cosmologies.
As others have noted, it’s also fruitless to try and make sense of the lore post-Chronicles. They’ve already retconned Chronicles 1, right? Saying it was all from a “titan perspective”?
Just make up your own explanation, or ignore Shadowlands and work with the manga lore 
Not everything has to be done by Titans. Infact we knew so little about Death Blizzard had the chance to make something up totally new from the getgo. And they did. I am glad they went this route. Trying to accridite everything positive in the Warcraft universe to either the Pantheon or the Keepers would be rather lame and lazy design. We will see how it plays out the following years.