For legacy implementation reasons, the backend service that published messages to Twitter would lose 1-2 queued messages every time the service was redeployed. Bleakly, the engineering team decided to not consider this a major issue, despite it being a core competency of the platform. It was simply extremely unlikely anything of value was being lost.
Obviously in the longterm it hurts value, but "doing things that don't scale" creates a lot of degrees of freedom (user growth, cashflow, funding) that you can use to pay off your "tech debt".
He could "Make Twitter Great Again" by killing the bots, and rage-engagement, and making Twitter interesting and fun again. If that raises Twitters value by 10% he gets a $4.5B return.
Publicly traded companies are too often affected by short sighted investors.
I don't think _only_ Elon can solve this problem, but one way of looking at the problem is that Twitter appears to be hesitant to 'solve' the bot problem because their most important metric that drives stock price is the number of engaged users, which includes bots. Taking twitter private (is this actually what Elon is doing? I haven't been following very closely) potentially removes the need to focus on this metric, freeing them to 'solve' the bot problem and not worry about the effect on the stock price when the # of engaged users drops by 40%.