The argument then happily visited the old "hypocrisy" charge, which says that we must dismiss as "wrong", void, null, and without force EVERYTHING ever said or argued by anyone (make that "any conservative") found to be deficient in his own exercise of principle (and excusing ourselves from having any principles at all, of course, if we're liberals).
Rush said that he had agreed to submit to periodic, if not random, drug testing as part of an agreement that he would not be prosecuted while he stayed clean over some period of time. Consequently people who blithely assert, as some do on FR, that Rush is on drugs now are guilty of "actual malice" - libeling a public figure in disregard of the fact that the libels are known to be false. If Rush were actually using drugs illegally he would be detected and would be prosecuted.