> Upgrading coal to gas is a great intermediate step. However, it’s not a long term solution because natural gas reserves are limited. Plus, many countries have already done it.

I don't see the author as arguing that we should all switch to natural gas.

Rather, I believe that they're trying to illustrate what they view to be a idealistic flawed thinking pattern ("utopian energy" or "green energy maximalism" or whatever you want to call it) and calling for a more rigorous and empirical engineering-like approach where a much larger trade-space is considered - even if that new approach leads to exactly the same conclusion/solution.