He shouldn't have blurred the text in [0], as blurred text could be read using techniques I admit knowing nothing about. It's better to just use a black block or something like that. Pixelating is bad too.

[0] https://cdn-images-1.medium.com/max/2000/1*h8cIVhi7n9-vuNJ-1...

Edit: I just noticed parts of the concealed text have been "smudged" before blurred. So no risk here. Still valid as a PSA :)