Very unlikely. Dalvag was a Highlander male stationed at the Halatali aetherial gate in 1.0; our Immortal Flame is decidedly Midlander. Additionally, the names of the soldiers the Immortal Flame calls out are of those who died in the Calamity--Dalvag died after the Calamity according to the hunter-scholar, during the Garlean invasion of Northern Thanalan (probably when they established Castrum Meridianum).
Off-screen and very quiet-like, but yes. Fairly certain you have to talk to Alianne outside of Copperbell Mines when you first arrive to learn this information.
Her exact words are:
We found Dolorous Bear and his entire party dead. The giants were...thorough in their work.
Judging by their tracks, it would seem they tried to rush a horde of the creatures. I cannot say for sure what drove an experienced crew like theirs to throw caution to the wind...but I do have my suspicions.
We are all our own worst critics, and our desire to better past achievements can rob us of good sense. Thus do we become more given to recklessness.
While it is important to have goals, one must not fixate upon them to the exclusion of all else. Do so, and one will surely pay the price, as Dolorous Bear and his comrades did this day.