They did it just in time for the debate. They are hoping to sink him with it on Sunday night.
Yes, this is being released because of the debates, but also because there was just a big dump of Hillary’s emails. The dem playbook is to tar and feather the opponent as quickly as possible to divert attention. The obnoxiousness of Kaine in the vp debate was this play to a tee. Pence couldn’t get the word “Hillary” out of his mouth without Kaine interrupting and pouncing on Trump. Divert, divert, divert.