The article mentions this only briefly, but browsers already do this kind of heuristic protection! See https://en.wikipedia.org/wiki/IDN_homograph_attack#Defending... or https://chromium.googlesource.com/chromium/src/+/main/docs/i... for a Chrome-specific blog post.

I think the lack of exploration of the context around the problem and current mitigations is an issue with the article - it spends a lot of time talking about the possible threat, but very little time on whether the attack is actually practical with modern mitigations.