Council of Elrond

Unique. Unless Leucaruth Ahunt is in play, Irerock has an additional automatic-attack: Dragon -- 2 strikes at 17/8.
In addition, only one unique Dragon manifestation may be played per turn.

Say Leucaruth at Home is in play and I'm travelling with my minion company to the Gold Hill. My opponent plays Smaug at Home during the m/h phase. Could I play Itangast Roused later in the site phase?

Doing a estrict reading of the card the answer would be no, and I haven't found any errata or correction about it on the CRF or digests.

Any thoughts?

You couldn't play Itangast - your reasoning is correct.