I think if you read the entire piece, you'll see that the writer believes that engaging in an illegal act - immigration or otherwise - is wrong, and it's a sin to be repented of.
Well, it's a law-abiding stance, and a comfortable and convenient one, too. But as a general principle is it a Christian position?
To take an extreme example (I should hope it's extreme, here and now) .... there was a time not a century ago when it was illegal in some places to harbor Jews. Should a church have avoided taking a contrary stand on the matter?
Or, perhaps more relevant today, would a Christian church be sinning if it took in and protected an Iranian Christian, here illegally, who was subject to deportation back to a place like Iran?
It's not something that a Christian church ought to take lightly, nor should it be a first resort. But a Christian church should never use the law as an excuse to avoid doing what's right.