Where have these claims been ignored? They got wide publicity in the various science periodicals and journals.
Though Pitman is ignoring that none of the claimed DNA finds over a million years old have been confirmed and are widely doubted because of this. The oldest confirmed DNA finds are for the Neandertals.
His carbon-14 claims are flagrantly false. See this.
The claim that intact hemoglobin has been found in T. Rex remains is an outright lie as well.