I think the story of the "process" kids are forced to go through makes me immediately think homeschooling (even though I don't homeschool). I hate infringements on freedoms, especially for really bright kids. I know educators would argue that it's their job and there's a pay-off, but I can understand your son's frustration with the "process". I don't like all the time taken to write sentences for spelling words (oftentimes too basic words) or looking them up and writing the definitions. There is value for learning the definitions, but not all that writing. It's agonizing for a little kid. It'd be agonizing for me, too, at 43. I'd probably have a tantrum, too. I say that and yet my kids do it, mostly without complaint. I treat it like busy-work that one must do even if you don't like it. Like mopping for me. Get it done fast, don't think about it again. Unfortunately, expository writing isn't the same as the busy work tasks, because it's your son's strength/passion. However, I worry that the process will turn him off entirely. I wonder if this would be a situation where you could intervene under the IEP umbrella of special accommodations. Once he demonstrates that he understands the concept and can employ it, maybe he shouldn't have to do it anymore. Move on. Let him use his own way. I don't necessarily practice what I preach, but I think it's okay to rebel sometimes and advocate for your son (he'll appreciate it and remember it--my dad was a very vocal rebel and advocated for his daughters all the time).
I feel the same way about showing work for math problems--it's so cumbersome for my son, but I understand it's value from an educator's standpoint. I'd like to negotiate showing the work for half the problems, or something less.
