Normally Open Cable Actuated Electrical Switch

The nearest Home Depot or Lowe's probably has about 57,000 varieties, or just turn an NC switch upside-down. The switch handles the amps, but it does not provide them.

Dillon make possibly the best of these.

Called a Dynaswitch force controller, they will easily handle the loads both electrical and mechanical that you specify and come in double throw configuration which will give you the NO contacts as required.

A quick search found them here

Google "rope pull switches safety". Most of the main electrical suppliers; Honeywell, ABB, Rockwell, Omron, Siemens make a version of this type of switch.

Look at the pulling force he wants. Normal rope/cable pull switches from the sources you mention are for emergency stop action and will operate at 15lbs of force. That would be useless to him.

My bad, didn't check the required force. Run the cable over two pulleys. Put a third pulley between the two pulleys but on the other side of the cable and misaligned so that the cable is deflected sideways. This third pulley is mounted on a sliding rod perpendicular to the cable and held forward by a stack of Belville washers acting as a spring. When the cable tensions it attempts to straighten by pushing the third roller back and compressing the spring. A limit switch at the far end of the rod can be set to trigger when the required tension is reached. This solution would work for both a static cable or one that moves under tension.