If they were "real people" they would cut and run when it became apparent they were getting slaughtered by the PCs. "Real people" don't fight to the death, especially when all they want is food.
I am with Mercurius on this. And am hard pressed to see it as a "trick" (I tend to run my games with some variations of this kind of stuff). A tragedy, sure. But a trick?
Also, the orcs may or may not cut and run, depends on how desperate they are and how bloodthirsty the PCs seem.
In a recent adventure in one of my games, a community of xvarts reached out to the PCs to help them deal with oppressive bugbears who had come in killed their chief and all his heirs and taken over, taking the best of everything for themselves, demanding the xvarts serve them, and killing those who complained.
The PCs decided to help, but the new would-be xvart leader also held back a contingency for dealing with the PCs in case they decided to start killing indiscriminately as adventurers (and from their perspective, humans) tend to do. Finding out about this, made the PCs worry they were being set-up and the xvarts were untrustworthy. Eventually, they decided that the xvarts had reasons to be distrustful of others and they would embody the good behavior they hoped to see in others.
My point being is that everyone needs reasons for how they act. They might not be good reasons. They might be reasons based on a flawed premise or an ideology - but "we're starving" works for me.
Years ago, in a group I ran there was a random winter time encounter with gnolls, who I decided were in a similar position as the orcs described above. They just wanted to steal the PCs horses to eat. The PCs had to decide if killing the gnolls over the horses or letting them have them was the way to go.