We have the habit of accepting only if supported by evidence or if its proved. So even thoug something is true we remain ignorant today if not proved and tomorrow if its proved we accept it. This has happened in mnay cases. As of now probably there are no hard core evidences which proves that Ram sethu was man made. But this Ramsethu finds a mention in our epics...so there is a possibility that it might be proven that it is man made if not today bu few years hence. So why destroy it. For that matter of fact no religious history be it any religion can be proven by facts.
For Hindus Ram is not just a Godly figure..he embodies everything that a human being shld be. Today if we can call Hindusim a tolerant religion and Indians tolerant to many invasions and the fact tht we are still secular it is because of what we have learnt from Lord Rams life and Ramayana.
So it makes little sense to destroy something when there will not be much benefit out of something. PLEASE THINK LEADERS