He is able to run the site on Tor just fine. The problem is that without being a normal clearnet site, your community will die off.
There is also the issue of it being super slow.
Notably, keeping javascript enabled during "Tor mode" even if the user has explicitly disabled javascript.
https://community.brave.com/t/tor-mode-always-has-javascript...
I recommend using Tor browser and using about:config to set javascript.enabled to "false".