The problem with Pantheism. Nature isn't God. And God is not Nature. He is the creator of nature. He has no family relationship with humans. So there is no blurring, no soft boundary between humans or a tzadik and the Divine
I want to mention as footnote that the faith of the Torah is Monotheism-not Pantheism.
That means that this God transcends nature. As the sovereign of all realms, God isn't by nature bound to any particular realm. Nature certainly becomes the stage of God's expression of his will. He expresses his will and purpose through forces of nature in the Torah. But nature isn't God himself. He's not identified [with it]. He's wholly other. He isn't kin to humans in any way either. So there is no blurring, no soft boundary between humans and the divine
That is that God created the world something from nothing-not from his own substance. And he is separate from the world and not a part of it. Holiness belongs only to God not to any other being like a tzadik -but God can make something holy. He does this when that thing becomes separated from the world and is so to speak owned by God. This is the concept of kedusha of the Torah. Purity is something else. It is the permission to touch something holy or to come into the holy place. Purity is not the same thing as holiness. But a lack of purity forbids one from touching or eating something holy. How does this relate to graves of tzadikim, I am not sure, but despite the many questions about that issue I think it is important to keep the most basic and essential beliefs about God of the Torah in mind.