I think the article is working with an extremely wide and weak definition of the term, which indeed runs into that problem. But I think that's a problem with the term being applied to anything "green and hopeful".

The point of the -punk label is that actively working towards a solarpunk world is pretty much punk because it's not where the powers in society want to go. E.g. a lot of it has an anarchist tendency because of self-reliance and independence ideas, it emphasizes slow down/simplicity vs corporate green high-tech projects, ...

The cliche solarpunk story is IMHO more "groups of people that break out in small eco-friendly communities" than "Singapore with more green".