We're not talking about preloaded HSTS. In such cases this change makes zero difference; Chrome already would have made the initial connection over HTTPS.
And it doesn't matter whether the legitimate server is refusing to serve plaintext HTTP if you're not talking to the legitimate server in the first place. The attacker can serve whatever they want.
Unfortunately, you can't be on the HSTS preload lists and have all newer browsers enforce HTTPS while still having a HTTP fallback for legacy systems. In genereal, the backwards compatibility story with HTTPS has been abysmal - it should have never been a new port or URL scheme in the first place.
Theoretically ISP can provide a transparent proxy to translate HTTPS to HTTP (but with some feature degradation). It could happen in restricted countries.
And the scenario where an ISP blocks https connections is unrealistic, the server can simply refuse to serve content on http other than redirects.