What would the behaviour of tearing one's clothes, letting one's hair hang loose, and shouting "unclean" symbolize?
These are all signs of mourning in the Old Testament (Ezekiel 24:17, Ezekiel 24:22; Micah 3:7). They symbolize that the unclean person is ceremonially dead. They have no access to the temple, the dwelling place of God, or the covenant community (Numbers 12:9–15; 2 Kings 7:3–14). They are cast outside of God’s presence and blessing.
45 “The leprous person who has the disease shall wear torn clothes and let the hair of his head hang loose, and he shall cover his upper lip and cry out, ‘Unclean, unclean.’