The twitter I found it on said it ran August 1st, 1974, 8 days before Nixon resigned.
The recording was ordered released July 24, 1974.
So it was not only released, but so recently released that it would be major headline-grabbing news everywhere in the country, yet old enough that there’s no way he could not have heard it yet.
Willful ignorance. We have a precedent. The Haldeman tape was fake news too, it seems.
EDIT: Dangit, the world operated more slowly back in those days. The court order was on the 24th, but Nixon didn’t actually release the tapes until August 5th. Nevertheless, the world knew they existed due to the Supreme Court case and subsequent order.