It's starting to look a little more clear as to why the unions are supporting this:
High Cost to Taxpayers and a Sweet Deal for Unions
This is the first FAA bill in twenty years to be introduced without a including a way to pay for the bill.
The 30,000-plus current ATC employees and all U.S. ATC assets would be transferred, an undertaking of huge magnitude and cost that H.R. 4441 does not adequately capture.
Under H.R. 4441, air traffic controllers would retain all the benefits of a federal government union, but would no longer be subject to federal salary caps.
These employees can also choose to stay in federal pension programs and continue to draw federal healthcare benefits, even though they no longer are government employees.
The special interest-run entity would be given billions of dollars’ worth of equipment originally paid for by taxpayers.
http://hotair.com/archives/2016/02/09/leaked-memo-shows-house-freedom-caucus-is-really-fighting-this-new-faa-restructuring-plan/