I'm wondering (outside chance) if it could possibly be the aircraft which is going to be leased by them to Atlantic Star Airlines around Q4 2015/Q1 2016. Technically the aircraft is being leased by Loftleiğir Icelandic but I don't know how the operation works anymore, I think it's all under Icelandair, hence them purchasing it. It could make sense as it is an ETOPS aircraft,
AFAIK, Icelandair has pretty high fleet utilisation so the couldn't use one of their own, and perhaps until they lease it to ASA they won't make any changes to the interior which may make things easier. Pure speculation but I don't know.