An interview with any of the known terrorists apprehended for attempting entry to US that revealed advise from US citizens (lawyers,"journalists" )as to how to gain entry into the country = aiding terrorists.
Pretty straight forward case.
Keep up
They are denied entry to Mexico because a country other then Mexico put them on watch list.
You need a reason to put someone on a watch list.
My guess as to that reason is somewhere along the line these specific people being denied entry gave advise to known terrorists as to how to enter the United States.
Helping such a person gain entry is against the law.
Now they no longer get to help migrants.
Well everything is pretty much a guess given the press today but that should be a given.
According to the article:
"She said the official told her the alert had been triggered by “the Americans.”"