It means precisely what I want it to mean, neither more nor less. Thus spake the Caterpillar, and the thought is catching on nationwide. Take the word "illegal" for example. Most of us imagine it describes something which if we did it, would get us in some kind of trouble with the law.
Not so in L.A.. The the Chief of Police has instructed his officers to ignore the word "illegal" if is might be associated with the other word, "alien" and let anyone this combination of words describes go on about his or her business after handing them a ticket. Secure in the conviction I guess, that the miscreant will dutifully show up in court or mail in the fine.
If this were L.A. statute, it would be bad. Since it's federal law, this sort of behavior is usually thought of as a Federal Felony, but only if you get caught at it and the Just-us department actually cares.