Since both Kelly and Mattis have disputed saying what's in the book, I'd think now would be a great time to bring out the tapes. I so hope he has both of them on tape making those statements, wow, wouldn't that be something!!!

Don't want to hurt sales

Most of what Woodward was told by sources in this book was on deep background. That means he can use the substance, but can't reveal the source. Obviously, playing the tapes in public would reveal the source.

Woodward kept Mark Felt's identity as Deep Throat secret for more than thirty years, and confirmed his identity only after Felt's own attorney outed him to Vanity Fair, and Woodward had Felt's permission to do so. He is not going to breach a promise to a source. In addition, he may not have Kelly or Mattis on tape saying what he quotes them as saying. It may be someone else (most likely more than one person) with knowledge they said it.

By far most of them would no doubt be draggingly boring to outsiders. Most of the time we wouldn't know what to listen for and miss odd words that didn't fit a picture we didn't have.

Lol. Woodward knows far better than almost all of Trump's staff what all those who came before them typically said and did. They have no idea how aberrational and deficient they are.

Or his career would be over

We won't hear them unless Spanky sues him, but that won't happen either.

My (rather limited) knowledge is that he's avoided doing so in regards to his books on Presidents Bush, Clinton, Obama and Bush.