It's not a crime to carry lots of cash. It is a crime however to smuggle proceeds of illegal transactions. Seems to me that sufficient reasonable suspicion was developed in this case.
It's not a crime to carry lots of cash. Tell that to the judge after your cash is confiscated. (Remembering that asset forfeiture is a civil process and not criminal: you lack certain rights and must prove your innocence, while the government has a lower burden of proof.)
Is possession of cash a crime?