I'm all for releasing a vulnerability after it a) is mitigated or b) becomes clear the responsible party has no plans to address the vulnerability in a timely fashion.
One day is in no way responsible unless the researchers were told pointedly that there was no plan to address the issues.
IMHO.
I really don't support people throwing around the DMCA, but if the company's lawyer's complaints are accurate (if) then IOActive sounds like they prioritized having a quasi-journalistic "scoop" over professionalism.
https://plus.google.com/118103547235676487972/posts/Sot7Tp1C...
Maybe they wanted to try to stealth-fix it without admitting an issue ever existed, and ran out of time?
Or it might be incompetence rather than malice. Maybe someone failed to take action until day 28.