This may be one reason :

Obamacare bails out union pension plans, too

Union bosses who have mismanaged benefits for their own members are poised to receive a $10 billion bailout from U.S. taxpayers in the form of a “reinsurance program” that has been folded into the healthcare bill, according to the Workforce Fairness Institute (WFI).
This provision should be viewed as part of a larger payback effort the Obama White House and top congressional figures have set up in exchange for the support they have received from organized labor, Katie Packer, executive director of WFI said.

DC Examiner