[tom_mellior]

A simple fix would be to pick a character that can not otherwise occur in Twitter handles, like ':'. Then move every inactive @foobar user to @inactive:2019:foobar. If a follower of the original account complains, change "inactive" to "memorialized" or whatever, possibly adjusting the year backwards.

If I choose to squat the now freed up @foobar handle and not do anything with it, next year they can move my inactive version to @inactive:2020:foobar and free up @foobar again for the next person interested in using it.

Any way they solve this, there is a danger of people using bots to mass-squat liberated names to offer them for sale. I don't see any very good way around this. Possibly to give first pick to users with long-standing accounts that share a nontrivial common substring with the liberated handle. For example, if my current Twitter name is @firstname_lastname, and I really want @firstname, I think it might make sense to prioritize me over @random_bot_204safhq23.

[lilyball]

Twitter's in a good position to detect most bots. If someone uses a bot that's good enough to evade detection, I think it's ok to let them keep the handle.