I wonder how one's refusal to speak with police, combined with the mounting judicial pressure against suspicionless searches would interact with cash seizure operations.

After all: '"We don’t have to prove that the person is guilty," an Albuquerque DEA agent told the Journal. "It’s that the money is presumed to be guilty."'

Would/do Federal rules governing asset forfeiture operations permit agents to use a search refusal as PC for a search of a person and their effects?

I understand that this discussion is largely an academic one. Realistically, if the officer really wanted to search and was otherwise barred from executing a search, he would make a "My knowledge and training told me that he acted like a terrorist." claim in order to provide PC for the search.