At the time I’m talking about the cause of the famine was an extreme drought, and all sorts of other problems as you allude to. More than population growth was war and instability - all great reasons to migrate if you could, but the lack of food is an even more common and compelling reason to migrate throughout human history regardless of the reason.
https://en.m.wikipedia.org/wiki/1983–1985_famine_in_Ethiopia
I didn’t assert the west should unilaterally open their borders. I stated that borders are inhuman - as humans are naturally migratory. Taking that to the real world, that would mean their neighbors should open borders as well - not just to Ethiopians, but to everyone.