Does the hiring of undocumented workers pose an exemption threat?

From what I have been able to find I would still say no. I have emailed others more knowledgeable than I and will let you know if they say different.

UPDATE - what they have said:
In theory, it should not be a threat to the exemption. However, this will depend on several factors, namely,

1. The type of exemption. A church will have a better stance than say a hospital.
2. The facts. Did the organization know they were employing an undocumented individual? What did they do about it when they found out?
3. How was it discovered? By the IRS, the organization, who?
4. Do they continue to break the law? Continued disregard for the law may jeopardize the exemption.