They did receive the complete set of books in the last go around with this lawsuit, in 1992. So to say asking for them again is simply a stalling technique makes an assumption that the players don't agree with. Should the books be opened, their auditors will get to comb through them, whether the owners were willing or not. You think the lawsuit is the goal, but I think the lawsuit is simply the means. Its the point of greatest leverage.
The owners are making a similar calculation. They believe that they can withstand the request in court (or NLRB) this time.
But I would love to read what you read about the owner's increased financial information offer and the change in the player's demand. I have not found it yet.