It is fairly clear from the various cut screens in the Romulan rep intros that DTan is asking for allied help for both Obiseks people and his own. The fight isn't gone from them, but they are asking for all sides to help them while they establish a new world. It is highly likely if Reman and Romulan are working together it is because both sides have seen the effect of dishonorable backbiting, persecution and warfare, enough bloodshed from all sides that they really just want to live amicably. There may be factions within their ranks that go back to the old Romulan xenophobic, dishonorable plotting, but most probably just want to settle down a bit.
Chingachgook told me, Don't try to understand them; and don't try to make them understand you. For they are a breed apart and make no sense.