The full version is in his hair test book--noamalgam.com. Excerpts are in googlebooks.
In short, the theory is that Hg fouls up movement--transport--of minerals into hair and elsewhere in the body. This results in statistically strange hair tests. He came up with "rules" for interpreting the test to determine if it is abnormal for mineral transport.
One of the rules is having too few essential elements in the green and white (normal) range.
Zinc is fairly commonly high or hi-norm in the detox groups. The theory is that Hg and Zn are congeners in the periodic chart--chemically similar. They compete to some extent but Hg is the big bully. This kicks out Zn from where it should be--so many enzymes, etc.