If your generator is super efficient your logic is correct for the generator, it is not much good for the prop.

To extract maximum power you must make your prop speed rise in the same ratio as the wind speed ( constant tip speed ratio), unless you at least approximate to this you will stall the blades and the power extracted will not rise with wind speed.

Your dilemma is to allow the prop to track wind speed and generate increasing power into a virtually fixed voltage.

I have indirectly covered this several times recently so if you go back through the last week or so's posts you should find something about matching generator power and speed.

Your gas generator is set to run at 3600rpm, under a load it uses more feul than it does at no load because it has to maintain speed and make the power, which takes feul.
It's all preset, runs at one speed and produces 120V at that speed and the more amps it produces the more feul it burns.

Now a wind gennie is not like that at all. It can turn however fast the blades will turn in however much wind you have. Yes cut in may be at 100rpm perhaps, but that is low watts in light winds. Heavier winds it may turn 200rpm and you will get more watts. And in really hard winds you have to furl it away from the wind or it will produce so much power it may burn itself out or the rpms be so high it will fly apart.
 Unlike the gas genny, with a wind genny you do not have anything to set the rpm to any constant number. Rpm will change with the wind and also the power the genny is making will change. Keeping a load on it will prevent it from free spinning in normal winds which could damage it. Free spinning with no load could result in excessive RPM in light or normal winds, a load prevents this.

Watts/volts=amps. So your batteries will hold the voltage down to around 13-14volts untill they charge, then your controller kicks in a dump load to use up the extra power being produced so the batteries don't over charge. Severals way that can be done.
 In normal winds this is what would normally happen. In really strong winds or a bad storm the tail section pivots and the genny turns out of the wind to protect itself from over speeding. Other ways to do it also, but most gennies built here seem to use the pivoting tail.

So maybe in 8MPH winds you have cut in at 100rpm and are getting 14Vdc at 2 amps, 28watts.
Maybe at 10Mph winds you have 200rpm and get 14V at 6amps, 84 watts.
At 20 mph, 800 rpm, 14V at 45amps, 630watts.
At 45 mph and above you may need to be furled out of the wind to prevent over speeding or burning out your genny.

The numbers are just numbers for examples not acurate speeds or power, but you get the idea.

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nothing to lose

Before the alternator starts charging, the blades will be unloaded (Free spinning) and running at higher than normal tip speed ratio, so it makes sense to design your alternator for cutin in 6 or 7 mph winds with a fairly high tip speed ratio.  (if you design the blades for TSR of 7, then figure cutin should happen in a 6mph wind at TSR of perhaps 9) - at least this seems to work well for me.

Certainly need good blades here, understood.