I'm no expert, but I guess if you disengage the load the turbine blades would accelerate until the internal heat losses to friction matched the energy input fro

I'm no expert, but I guess if you disengage the load the turbine blades would accelerate until the internal heat losses to friction matched the energy input from the wind. In other words, they'd spin very quickly, probably far in excess of their design speed, meaning at best that they would wear out much more quickly, or I guess more likely RUD (rapid unscheduled disassembly), causing them to be considerably more dangerous.