Do you have a source for this? The only thing i can find is a random tweet from Elmo in 2023. I deleted my twitter account in the 2022-ish timeframe, and the handle I had (created in 2007) was my first initial + last name, which I would think would be claimed by now. It's not, so I'm thinking that deleted account handles can't be reused.
So it seems unlikely they would keep deleted handles forever. I bet they become part of this marketplace program a la "premium domains".