These are not synchronous grids, but some other kind of boundaries. With synchronous grids the US should be split to only 3 zones, and most of Europe would be colored the same. So I think the kind of map you used is not the best for this joke.

World map of all synchronous grids:

From the website it sounds like that is a map of electric companies or something like that. So this map is not directly related to the Texas crisis. Most of these companies share electricity between each other.

Tom Scott video about synchronous grids: https://www.youtube.com/watch?v=bij-JjzCa7o

More info: https://en.wikipedia.org/wiki/Wide_area_synchronous_grid