An update: Emerson had an R1 swingarm and shipped it to me. Turns out I was unfortunately right. The swingarm was in fact damaged. Without even measuring how "straight" or "aligned" it is, initial measurements from the inside of the axle slider portion of the swingarm on one side to the other is about 5mm narrower than it should be.
I believe that when the left adjuster sheared and the right one didn't, with me being hard on the gas, the motor was pulling hard on the upper chain, pulling hard on that rear sprocket, which pulled the left side of the axle straight forward but the adjuster on the right still being intact kept it from moving. This meant that the axle would be at an angle, "squeezing" the swingarm together very hard. After thinking about this, I'll also need to inspect the wheel bearings pretty carefully as well.
Tomorrow I will be swapping the swingarms. Thanks to Emerson for taking care of me!
I believe that when the left adjuster sheared and the right one didn't, with me being hard on the gas, the motor was pulling hard on the upper chain, pulling hard on that rear sprocket, which pulled the left side of the axle straight forward but the adjuster on the right still being intact kept it from moving. This meant that the axle would be at an angle, "squeezing" the swingarm together very hard. After thinking about this, I'll also need to inspect the wheel bearings pretty carefully as well.
Tomorrow I will be swapping the swingarms. Thanks to Emerson for taking care of me!