I agree with you. The government knows. Why keep this from the people? There is something profound enough to merit the secrecy. Finding a body won't change the decision to keep it a secret. It will only lead to an aggressive cover up effort.
How could you release it without being stopped by the government? Youtube? You'll be called a hoaxer. Sending the DNA to someone? They will be silenced and discredited. Sending it to a university? Their funding and grants will be threatened. How can you overcome the machine that is designed to control the info? Not saying its impossible, but it will require an in depth, multi threaded plan.