If you were to break the statements down you notice that,
- (Before becoming a conquistador, Pizarro had worked as a butcher back in Spain.)
That statement doesn't make any sense. Cross that out.
Next (Pizarro had strong hands and the knowledge of the animals common to many butchers.)
This shows nothing about why the men "would" call him that.
That leaves you with 2 Choices.
The one that makes the most sense is ---> "Pizarro was so determined to conquer Peru that he ignored hardships faced by his men.
Hope that Helped!
~Izzy <3