I would think that soaking in dish detergent and water wont hurt it much, but honestly, why? Typically, I go about cleaning cranks and derailleurs by leading off with a deluge of WD40, then a toothbrush-scrubbing, then a blast of air to free it all up and clean it all out. Usually that does it, and its lubricated and corrosion-treated all at the same time. I've been doing this for decades, and never had a problem.