When it comes to El Salvador, there doesn't appear to be an argument that people can simply relocate to a safer part of the country (let alone find a job there). The US will have a difficult time saying that it will only receive refugees who've fled from X and Y departments and not the rest. Of course, there remain municipalities void of large-scale violence. However, the safer, more humane course of action, seems to be to extend refugee, humanitarian, or temporary protected status to those Salvadorans who've left their homes for the relative safety of the US.
I don't know how long such protection will be required but we'll cross that road when we get to it.