He isn't really opposed to immigration, especially not in the end. He simply believes that, "because it is the law, it must be correct".
When a countrys citizens doesn't dare consider if the law is correct or not, something's wrong. The people are sheep.
They assume the law should be there, they assume it can't be corrected or perfected. He objects to the senate changing the immigration law, with the argument "it's the law". He seems unable to consider the fact that the law could be a bit wrong.
This is something that has to change in America. The people in America have to start getting more active in reading up and taking action when it comes to laws and politics.