If they are not so limited in their comprehension, as that would imply, they have chosen to deliberately put their perception of their own self-interest over the legal rights of the American people.
Whether their lack is of intelligence or morality, no long term good can be expected from allowing them to remain. Those who for the sake of cheap labor--for a perceived advantage of the moment on this side of the border--would rationalize amnesty, are sewing the seeds for a future disaster. A nation is not a game of musical chairs. And this attempt to justify the present chaos is terribly misguided.
For a serious look at the whole question of future immigration, see Immigration & The American Future.
William Flax
Here is their exact justification: