What you quote was a tweat or a transcription from a stream or something like that. The official stance to what is canon was given by Perkins on the D&D website:
D&D Canon
Here is the quote
@Maxperson and I where talking about:
"Fifth edition’s canon includes every bit of lore that appears in the most up-to-date printings of the fifth edition
Player’s Handbook,
Monster Manual, and
Dungeon Master’s Guide. Beyond these core rulebooks, we don’t have a public-facing account of what is canonical in fifth edition because we don’t want to overload our fellow creators and business partners."
Though I suggest you read the whole article.