I think claiming what the Dems what is an open borders policy is much like the socialists comments from the right. They are statements they make without thought because they are too simple minded to understand semi-complex ideas.
Saying a wall won't work and we shouldn't separate children of illegal immigrants from their parents isn't advocating open borders.
Much in the same way that government run healthcare is not socialism.
That said to be entirely fair the Democrats do a similar thing with abortion, thinking that if we don't have legal abortion we are turning women into property.
What's so "semi-complex" about enforcing the immigration laws passed by Congress?