Yes, Peru should ease restrictions on investment near heritage sites, because economic activity near the sites would ensure their survival. Allowing investment near the sites would encourage tourism, and would make it easier for more people to come and visit the sites. The investors would want the heritage sites to survive, because the sites would bring them business.
Peru should not ease restrictions on investments in any case. Easing restrictions on "investments" is just code word for corporate takeover. We need to stop pretending things like this have some sort of ethical or moral motive, or that they are innocent. Let's be honest: we want to open areas up to corporate takeover.