My initial reaction too was what is going into that blender? Been watching too many Criminal Minds episodes lately so I'd rather not know.
If you do have a 2KW blender, that's could be up to a 2 horsepower motor in it. The usual ballpark rule of thumb is 1HP = 1,000 watts. My tablesaw has a 2HP motor..... (My tablesaw could cut up an entire moose, bones and all no problem.)
Without delving into the details of how the blender is designed, am not sure if the solid state part of it might cause any issues. Might and might not. Harmonics can sometimes cause problems created by solid state controllers and power supplies.
You generator size is 3.6KW. It sounds like you may need a generator of around 4-5 KW just to get the Blendtec started. Then, if you have other loads you want to run at the same time like say a toaster, then you'd want to increase the generator by another 1.5KW (or by what the "other" load requires). Then you you could need a 6KW or larger gen. and you'd have to figure out how to plug your 30 amp RV plug into it. Or if it had a 15/20 amp recept on it, you could plug it in directly.
Don't think power factor is an issue since you need to have a gen. 2 - 3 times the power rating of the blender.
One other thing - the cable/wire overall length between your. gen. and blender *might* be part of the problem. Since you may be getting inrush current of up to 6 times the full load amp rating of the blender, the voltage at the blender on starting might be too low. Try plugging the blender in at the generator and see if that helps. As you may know, the HP output of a motor varies as the square of the voltage. This means that the motor may be underpowered to get it out of the momentary starting "locked rotor" condition and the generator can/will stall out. I supposed you could try a voltmeter at the blender on starting to see what the voltage reads.
And another thought - I think for some of the small portable generators out there, that the power output ratings are not that honest.