That's why I asked. If they have strong convictions they'll tell us instead of just whistling.

Implying Ta-Nehisi Coates is a low bar is absolutely a dogwhistle. What context would change that?

The OP stating their reasoning explicitly would give that context. Generally people that are dog whistling don’t like to be explicit

First, let's clear up the terminology. When someone says "Their bar is not uniformly high...", that is not a dog whistle whose meaning is unclear except to a certain group. It is a simple statement that the referent does not meet a high standard.

As for the reasoning, criticisms abound, but two (one recent and one older) are:

https://www.politico.com/magazine/story/2015/07/the-toxic-wo...

https://colemanhughes.substack.com/p/the-fantasy-world-of-ta...