But it's also listed on http://cbl.abuseat.org/lookup.cgi?ip=5.104.224.5 as

If you find exits on blacklists, you could try to contact the operator via their descriptor contact, exit http banner, etc so that they can try to have it removed. Usually a few clicks on an assertion of ownership/cleanliness and an email ack is all that's needed for removal. Since ownership of IP's is always in flux from perspective of BL's such that any 'real' owner could always do it too, absent exit contact info, many users could probably submit removal for them without issues.

There's a project covering this on the wiki: https://trac.torproject.org/projects/tor/wiki/org/projects/DontBlockMe