Someone was having the same issue with The World’s Finest earlier. I haven’t tried that site, but with Platypus Comix, just platypuscomix.net gives me TZ’s homepage, but www.platypuscomix.net works fine for me. Not sure how that works. Something else I find odd is that the URL in the address box doesn’t even change. It still has the Platypus Comix URL.
Relating to this issue with The World’s Finest, James Harvey said that some server work is being done and that there may be occasional hiccups in the service. That’s probably what’s happening here.
Another oddity: When I use my MacBook's Safari browser to visit Platypus Comix, I click the "Siri Suggested Website" that appears when I type the address, and I manage to find the homepage. However, trying to click anything on the homepage brings up a "Page Not Found" message from ToonZone.