I remember seeing a leftist meme that joked something along the lines of "herrderr, the right is so stupid they have to use coloring books" and referenced this book.

This is the only example of a coloring book that's "right" that I have ever seen. And it's not even explicitly geared towards adults, it could easily be given to a child who likes their president!

Meanwhile if I walk into Powell's Bookstore in Portland they have literally a whole fucking section of specifically adult themed coloring books about leftist ideas and political concepts.