It's a nation of 300 milllion plus. Passports are lost and stolen every day. Sad as it may sound, they cannot excitedly respond to every passport gone missing. If I were you I would worry first and foremost about identity theft, because that and not terrorism is teh likeliest motive. Then again I suppose they would eventually sell a passport to smugglers or something. But with computerized systems, a reported passport might be a red flag. Also, your passport could be in a storm drain or wherever it blew into when the postman dropped it.
maybe not terrrorism, but it could be used to help illegal aliens, money laundering, identity theft, smuggling drugs from overseas...etc.