If the Rams are OK with Donald's demands, and he simply wants to wait until Mack signs, then holding out makes no sense at all. To prove what? That he won't take yes for answer to his contract demands? Or that he won't even give his final demand until the Mack deal is done? Then it doesn't matter what the Rams offer.
Can't buy that theory.
But, as the article said; he MUST report by August 7 (2 days before the first pre-season game) or he becomes a RFA and not a UFA at the end of the year. He'll report. And he'll have nearly a month to be ready for the 1st regular season game. That's more than enough. He was never going to play in the 1st game anyway, and likely not until the 3rd if he reported to camp on time.