No, Bruno - there is something else going on.
The view that you have in this article is reserved for search engines. Normally comments are loaded with an ajax request in the background -> in your case this is what search engines see when they visit the page. Can I have a look at your background?
The issue is with sh404. If you turn it off and go to the article you'll see that the comment system works.
It actually turned out that the problem is not sh404, but the joomla cache (I guess that when you turn off sh404, it clears the cache).
CComment is not going to work with Joomla's cache turned on.
The problem is - Joomla is trying to cache the output of the whole page. Which is theoretically fine, but it is fine only for static content & not dynamic one. Comments are dynamic -> I need to know the user that is currently browsing the page etc.