The Good Samaritan was the one who did the "helping" -- he wasn't the one who was being helped. So the parable would only have any relevance to HR 4437 if the proposed legislation prohibited wealthy Mexicans from embarking on charitable ventures here in the U.S.
I don't "misunderstand" the Parable at all. Please guarantee that the following will NOT be used against some modern-day Good Samaritan offering food, medical care, and a roof over the head of an illegal alien:
". . . assists, encourages, directs, or induces a person to reside in or remain in the United States, or to attempt to reside in or remain in the United States, knowing or in reckless disregard of the fact that such person is an alien who lacks lawful authority to reside in or remain in the United States"