Webfaction hosted servers are behind firewalls/proxies. Unlike standing up apache (i.e., socket:xxxx on localhost), their wordpress installation appears to simply be the wordpress code. Therefore, they appear to application route the WP requests vs. NAT/firewall the TCP.
I would guess the civicrm plugin doesn't pass "HOST:" http headers ...
yes, no, solutions? (see pict)
Note:specific menu items (e.g., Administer-> System Settings -> Option Groups) render fine. (and, that messed up CSS is probably due to the 404 page's css)