Shadow's website has been 404 for at least two months now. Mail to the mailing list is undeliverable. Mail to the maintainer does not get answered.
And, we should do exactly what? :-)
Mark it as dead, you silly cow. Remove "http://shadow.pld.org.pl/" from the ebuild and say it is dead, gone, lost instead.
Except that HOMEPAGE cannot be empty. Absolutely no need to offend anyone here.
Then replace its content with "d0d0, DEAD". What's the use of pointing the user to a non-existent page? -- Or at least prefix the URL with some indication that the website is dead. Present accurate info, not a false hope.