Bankruptcy just allows XFL to avoid paying debts. McMahon may be a jerk, but he's no dummy. Undoubtedly put just enough personal money into the XFL corporation to keep it afloat, and was banking on gate revenue and TV to fund year 1, and then put more personal money in for year 2/3.
Business 101 playbook. Separate personal funds and corporate funds as much as possible. Corporation is successful, hooray, pay owner dividends. Corporation tanks, when corporate funds are gone, declare bankruptcy and protect personal money.