There are many Part 135 cargo ops on small planes which only require a commercial certificate. For these, you only need 500 hours TT to serve as a PIC in VFR conditions, or 1,200 hours to serve as PIC in IFR conditions. See 135.243 for details.
Ameriflight requested relief from the 1,200 hrs IFR requirement for certain ops. They proposed a modest reduction in hours (to 1,000 hrs) but in return the flights will only be authorized when the weather is forecast to be at least Marginal VFR (ceiling > 1000 ft, visibility > 3 miles, etc.) Pilots operating under the waiver will only be allowed to operate small non-type rated aircraft, carry no passengers, and have some other restrictions placed on them (e.g., no night circling approaches). They are also subject to additional training and check rides.
I believe they mainly use this waiver as a bridge for pilots who participated in their SIC program (to 1000 hrs) since they will be 200 hrs short of the full 135.243 requirements.