Without wrapping it's just a collection of very long lines that won't display nicely in something like w3m.
Maybe calling a "web* site is a mistake. Why not proudly announce it as an RSS site and mark the feed protocol accordingly?
So if someone's feed extols the virtues of RSS feeds the only option for sharing that is to share the whole feed. If someone checks the feed a month later that great point made may no longer be in the feed. Since it doesn't exist as a post on a website it's just lost. No no one will ever be convinced RSS is the end-all be-all of blogging.
I’ll concede that at that point, a mailing list may be preferable to the RSS feed in the first place. Or Usenet.
UPD: It's working now, after switching RSS-feed "Type" to "RSS 2.0/2.1" (by default RSS Guard set "ATOM 1.0")
[0] https://tdarb.org/feeds/posts.xml
[1] https://github.com/martinrotter/rssguard/releases/tag/devbui...