I don't know how you can argue that isn't true - loading up Github runs all sorts of javascript you can't reasonably inspect or control. Whether or not that is a bad thing, or, how bad it is, is certainly a reasonable thing to discuss, though.
They have rest and graphQL interfaces for all the functionality that isn't plain git. You don't need to use the github website.
I use the graphql api to build a set of shellscripts to do all my pull request reviews on my terminal using vimdiff for example. I can then approve or reject things just using shell and not touching the web frontend at all.
His actual point, in context, was that GNUstep shouldn't be hosted on GitHub because in doing so the GNU project is effectively inviting users to run GitHub's non-free software on their computer.
Does loading the page in a default-configured browser execute non-free javascript on your machine?
Is the page usable without disabling the non-free javascript?
Can you learn how to use the API without using non-free javascript on their documentation pages?
Is forcing someone to learn to use the API directly and interact with Github purely programmatically a reasonable alternative?
And finally if the non-free software is removed from your machine but interaction still relies on non-free software on the API side is that really any better for the end user?
