upekkha100: It does not say good roots are removed; please read it carefully. It says, those kamma done with good roots will not bring vipaka anymore.
That is because, one has cultivated all sobhana cetasika (including panna) to the optimum (so the good roots are working at optimum), and thus will not grasp a new bhava via, “vedana paccaya tanha“, “tanha paccaya upadana“, and “upadana paccaya bhava“.
– When there is no new bhava, there will no new jati to experience even those good kamma.
This is an important point. So, let me explain a bit more.
Just because there are causes, the results WILL NOT follow if CONDITIONS are removed.
– That is what is explained in Paticca Samuppada.
For example, a seed may last thousands of years, but WILL NOT bring about a tree unless suitable conditions (i.e., soil, water, sunlight, etc) become available.
One’s good kamma beeja may be there, but they will NEVER get an opportunity to germinate once one removes the “bad three roots” and cultivates the “good three roots” to the extent that one will never go through the steps in Paticca Samuppada starting with “vedana paccaya tanha”..