the special black paint that retains the heat at night and makes it just as sizzley at 3:00 a.m. as it is at 3:00 p.m.

I probably shouldn't give the formula away, but all you have to do is mix snake oil with plain ol' ordinary black paint.

Kristi Noem et al will pay billions for it!

/end snark tag

I'm not sure how that would work, since the north side doesn't get the direct sunlight that the south side gets.

But maybe it sounds good to the Base.

It's performative nonsense as you said, designed to impress the MAGA base

and that is the only thing that matters to him, his base, and the lapdog media that obediently lap it up and regurgitate it every GD day.

When the repubes do the opposite - spreading inky painful darkness -- that makes their true nature clear.

How sad.

The contrast between the two sides of the fence is striking and well worth pointing out, but the post title is wrong and actually contradicts the source in the body of your post.

Your title says that the murals are a response to Noem's black paint, but, as the tweet in the body of your post points out, the mural painting is years old.

Here's a 2018 article on the murals, with the same mural photo as used in the OP tweet:

https://www.businessinsider.com/mexican-artist-enrique-chiu-border-wall-murals-2018-1

A Mexican artist is painting the 'world's longest mural' on the US-Mexico border wall — take a look
By Leanna Garfield
Jan 7, 2018, 10:00 AM ET

Link to tweet