There is the problem, in that snippet of a quote.
You are regarding an inherent quality and something to be realized as two mutually exclusive things. They aren’t.
There are a few Buddhist parables which illustrate this. One is of a poor person who doesn’t realize there is a valuable jewel sewn into the pocket of his coat. He goes for years barely having enough to get by on. Then, one day someone points out the lump in his coat. He rips the seam and discovers that the whole time he was quite wealthy.
The point is, all beings have the potential to realize the inherent quality (Buddha-mind)
that they already possess, but don’t yet realize. That’s why realization is something you attain, and not obtain.
We are all Buddhas, ultimately. But, because of our obscurations, we just don’t realize it.
As I mentioned previously, the big question is how can Buddha-mind be obscured by anything and still be called tathagatagharba? But again, it isn’t obscured from its side. Your enlightened mind is always functioning. You wouldn’t be on the Buddhist path if your Buddha-mind wasn’t functioning. But that’s a unique quality of beings on the human realm. It’s just the same as the Sun always shining whether we are in the shadows or not.