I wrote a short seven-point response in the comments lucidly explaining its most obvious problems, and signed it Summer Glau. It got removed, and I learned a valuable lesson about productively channeling my anger.

I'd look at what you would have spent your time doing otherwise before you necessarily say (you didn't, but implied) that was a waste of time. Even if exactly 1 person read it (the one who deleted it), you got practice expressing yourself and (hopefully) coherently forming an argument.