There was at least one unnamed, previously unseen red shirt on the bridge as well. That was a hint there was going to be a body count. Of course, it could also mean that no one dies and the production staff are just playing into our expectations.
Ortegas was in the alternate future with Pike at the time of “A Quality of Mercy”, which is not necessarily “plot armour” but if we assume the timeline still hasn’t diverged — Pike not having had his accident yet — then it would seem reasonable she should get through to survive long enough to see the point of divergence and therefore survive long enough to be on the bridge with Pike when he meets the Romulans. However, that’s all very timey-wimey and subject to a lot of “maybes” and “what-ifs”.
A Quality of Mercy also showed Una in prison, and Those Old Scientists implied she’s revered. Did sending that letter prevent Pike from recruiting her lawyer? Things are already not heading down the exact timeline we saw Ortegas alive in.