"..concerning other methods, ie those used to date rocks , these also rely on unproven assumptions about the past of any particular sample."

Pete... that is a double error in one sentence. They are not really 'assumptions', they are DATA, based on proven science, which are used in order to describe the 'past' of the sample!
Your continued insistence on contradictory data being associated with *some*specific samples is just a misunderstanding about how the analysis is done, plus an insinuation that this is common... it isn't! Most geologic samples do NOT have mixed results, and those which do can be examined by scanning electron microscope and in other ways to determine HOW various media became co-mingled. (I once found a piece of nut shell in a candy bar and almost broke a tooth. It made me 'careful' about eating candy with nuts, but I didn't suspect the basic procedures of the company. Sometimes, odd things get mixed due to accidents, but we can still analyze them. )