[semiotagonal]

If you want a short-and-simple username, you need to do what it takes to defend it, even if that means logging into twitter once in a while. Even registered trademarks require active defense, or they lapse[0]. Why should it be as easy as just grabbing it first, especially if that pollutes the platform in a way that hurts the platform company?

If you want an easily defended but unique identity, pick something that isn't short-and-simple, and you'll have less competition.

[0] https://en.wikipedia.org/wiki/Laches_(equity)