Not entirely. They asked for 180 days, they got 90. That's all they get. They can get "until appeal" if they file an appeal, which must be noticed within 14 days (well within the 90), and if so, the clock starts on briefs (which are due well within the 90 days). If they don't file briefs, they won't get a stay pending appeal, or if it was granted, Gura can get it lifted.
If DC passes legislation, the appeal is null and void. They can ask the CADC for another 90 days (getting the 180 they originally sought) but not based on the reason of "pending appeal". It would be an appeal of the judges failure to grant the 180 day stay. I suspect they will not win that appeal of the stay motion given the behavior of Illinois stretching 180 days into 360 days. A stay pending appeal would not have a time limit, but it would be very much tied to their actions on appeal. If they do anything to stop or delay the appeal, Gura has an opportunity to smack them on the issue.
Given this set of facts, there is very little likelihood DC can get more than 90 days without filing substantive pleadings in an appeal. The only way they can get more than 90 and not see an appeal all the way through is for the legislature to pass a law midway into the appeals process. They would look like morons if they do that. But that's the only way I can see it happening.