The prospect of bioterrorist attacks was not yet pressing the popular consciousness. He had the antidote for an attack and limitless earning potential. All he needed was a catalyst to cause mass panic to get his product stockpiled. It's the simple law of supply and demand.
It's not so cynical after all to wonder if terrorist attacks are caused primarily by profit-motives. Bioterrorism is first a marketplace and fanaticism seems like a cover for the hard exchange of goods and services.