They'll have to address it now.
Actually, I found the nail in the coffin. Eufa's rules make the distinction that matters. From their mouth:
http://www.uefa.com/MultimediaFiles.../Regulations/01/63/02/44/1630244_DOWNLOAD.pdf
Pages 6/7, Rules 2.03 a and b account for 2 possibilities. If Chelsea hadn't won the FA Cup and qualified for Europa already, then we would have been been handed the "additional place". However we fall under option a, no more places.
2.03 The UEFA Champions League titleholder is guaranteed a place in the group
stage even if it does not qualify for the competition through its domestic
championship.
a) If the titleholder comes from an association entitled to four places in the
UEFA Champions League and qualifies for the UEFA Europa League
through its domestic competitions, the lowest-ranked club of the
association’s UEFA Champions League representatives is automatically
transferred to the UEFA Europa League (into the latest possible round
where there is a vacancy). In this case, the number of places to which the
titleholder's association is entitled in the UEFA Champions League and
the UEFA Europa League does not change.
b) If the titleholder comes from an association entitled to four places in the
UEFA Champions League and does not qualify for the UEFA Champions
League or UEFA Europa League through its domestic competitions, the
lowest-ranked club of the association’s UEFA Champions League
representatives is automatically transferred to the UEFA Europa League
(into the latest possible round where there is a vacancy). In this case, the
association of the titleholder is entitled to one additional place in the
UEFA Europa League.
Such a fine line!
PL just butchered the wording of this rule.