I'd argue that shamelessness and countersignalling are different things but share the same foundation: confidence.

Shamelessness is acting without embarrassment and countersignalling is deliberately downplaying because you're so confident you don't need to prove yourself.

Using the example from the article, another person who comes to mind besides Paris Hilton is Trump. He uses countersignalling as a strategic tool, and sloppiness as a Swiss knife. The followers of both Paris and Trump interpret that sloppiness as confidence and authenticity, which is why it's so effective. And to pull off being deliberately sloppy, you need to be shameless.

I don't think it is that deep for Trump. His sloppiness is great for the media because his choices lead to endless content. He is great for the unofficial media because everything he does is meme worthy. It is no wonder he and Musk teamed up, both their successes come from following the same strategy.