It's a habit of the community. Tao actually elaborates on what he means by this in the same paragraph.
I'd like to offer a charitable interpretation. By Tao labelling it as "remarkably elementary", he encourages less experienced mathematicians (including students) to go and read the proof for themselves. He's advertising a low barrier to entry for certain parts of his audience. This isn't always the case with whatever he reports on, so it's worth pointing out when it's true.
I'd like to offer a charitable interpretation. By Tao labelling it as "remarkably elementary", he encourages less experienced mathematicians (including students) to go and read the proof for themselves. He's advertising a low barrier to entry for certain parts of his audience. This isn't always the case with whatever he reports on, so it's worth pointing out when it's true.