That would be a nasty compromise. Redirecting lynx users to a sex page that doesn't even render in lynx. Tsk. Seriously, the helpfile url does look like a valid url and probably belonged to the lynx maintainer when that url was entered as the default helpfile url in lynx. To get around the problem, you could enter the following line to /etc/lynx.cfg:
HELPFILE:file://localhost/usr/share/doc/lynx-{version}/lynx_help/lynx_help_main.html
Where {version} is whatever it is on your system.