Pointing out that "abuse is whatever an abused person defines it as" is an argument built on quicksand is very much not bikeshedding.
Ok, in that case lets also catch the low hanging fruit of black men raping white women. And if you say "a black man asking out a girl who doesn't like him isn't rape" then you are guilty of bikeshedding. <- Spot the fallacy yet?
If circularity is valid then as a victim I define names that start with "brei" to be harassment. You can tell I'm a victim because someone with a name starting with "brei" replied to me, which makes this valid. <- Spot the fallacy yet?
Consider the possibility that if you can't prove your point without deliberately resorting to logical fallacies, that your point might be wrong.
But since you seem to think that there is a fully-cohesive, non-circular, objective way to judge what is harassment or abuse, please enlighten me as to what it is.
If you fail to do so, then somebody will probably rape and kill your entire family. <-- Not abusive, because there isn't a peer-reviewed Theory of Abuse available.
edit: Just for the hard-of-sarcasm, the last bit is to illustrate the ridiculousness of the argument, not an actual threat.
Which is exactly the bikeshedding that @nstart referred to about 6 posts ago. Thanks for yet another near-perfect example.
And while I get your point about circularity, it pretty much has to be that way. For example, if I threatened to stab a random person with a syringe, that would be abusive. If I threatened to stab my brother with a syringe, that's an inside joke from when we used to play "Battlefield Vietnam" together.
Which is pretty much what the article was getting at when they talked about context mattering more than content.