Looks like RAH dropped their 150M claim which resulted in creditors receiving 18 cents on the dollar or 50% more than the SWA offer of 12 cents.
Frontier seeing clear skies - The Denver Post
"Republic's offer also was more attractive to Frontier's other creditors. By dropping its $150 million claim for a terminated flying contract, Republic bumped the return for creditors from about 9 cents on the dollar to 18 cents on the dollar.
Southwest's bid would have paid creditors about 12 cents on the dollar."