The healthcare, the stock market, hiring practices, or several other issues are important and need discussing, but aren't particularly relevant to the conversation on illegal immigration/evasion of security screening.
In context of the thread's title/subject, this isn't a red herring.
We're talking about illegal immigration and how it affects African-Americans, not the US' position on illegal immigration as a whole.
In that context, my point is relevant, so your attempt to rule it out as a red herring is invalid.
Also since you're concerned about domestic terrorism, you should be concerned about anyone evading security screening/background checks by skipping the immigration line and crossing illegally.
Believe it or not, it's not that simple.