That still doesn't make sense. To prove they checked the form wrong, you have to prove the actual charge itself (e.g. they are a terrorist, by whatever definition). That itself is enough evidence for deportation.
Except the question is "are you or have you been in the past associated with, do you know of, are you a relative of a know or unknown terrorist or a terrorist organization?" (The real question is longer)
Then a similar question for nazis, intelligence agencies, military and some more.
There is a podcast of a story of an immigrant who was associated with a group as a kid. Decades _after_ him immigrating to the US the US declared the group a terrorist organization. Will post the link if I find it.
You may have misunderstood - I think the parent is saying its the same principle as, say, convicting Al Capone of tax fraud. Create a large number of small, easy-to-accidentally-violate laws (think police stops and traffic laws here), and then selectively enforce them - so if its difficult to prove someone is a terrorist, kick them out of the country for incorrectly filling out their Form WhateverWhatever1300B instead.
They got Al Capone on tax evasion (not fraud) because he evaded taxes, not because of some grand scheme. The IRS is interested in collecting taxes, not policing.
On a related note, the IRS also requires that you report and pay taxes on all the money you made by robbing banks, selling drugs, and embezzling your employer's coffers.
Nobody who hasn't already been convicted will fill out those forms, of course, but that's another criminal charge if the DA wants to put you away for even longer.
It’s also easier to arrest someone on suspicion of falsifying customs forms and hold indefinitely than to do so on “terrorism” charges.
So this does indeed give law enforcement a lot of leeway than not having it is.
So, to answer your question, yes.