Again we see phrases “...its appearance is deeper than the skin” the subject is unclean and “...it is not lower than the skin” the subject shall be quarantined. This would suggest again that this is about who we are vs. what we look like.
In Judaism, you should always rebuke someone who is not doing the right thing, but never embarrass (which is like killing) them. Wow! What a challenge. The external scabs both humble us, and let others know that we are not G_ds. They invite rebuking. Wise men appreciate criticism. How did they become that way? Did they listen?