Uhh, Yes? It is literally probably what this machine was doing in 2001.
(Source: guy who hosted websites on sparc's in 1995)
(Source: guy who hosted websites on sparc's in 1995)
UltraSparc smoked Intel at web server response times because it could handle so many more threads for Apache.
I realize that reading through the article that they did get OpenBSD working on there and yeah if you can get a modern OS on there it will probably work fine, but I don't think the core question of "Can my SPARC server host a website?" is dumb.
It's not a dumb question, but OP didn't answer it. Cloudflare is fronting the website. So we don't know if the server is handling the entire traffic, nor if it's using TLS between it and Cloudflare.