Did you actually read the rules?
"Template engine websites, tools, and sites that generate HTML from text, markdown, or script files, such as Webs, Wix, Weebly, GitHub, Jekyll, and Replit, are NOT permitted."
That rule is NOT clear; it implies that Github is forbidden specifically as a "site that generates HTML". There's no reason to interpret it as meaning that you can't even link to a service that happens to provide templating and HTML generation, and which you are actually using only as a SCCS.
I would certainly interpret that rule as meaning that you can't use template engines or HTML generators. Which they didn't. I would not interpret it as meaning that you can't use anything provided by a service that ALSO supports templating and code generation. The teacher was a dick.