Twitter has been active trying to get rid of trolls or limiting their reach so when they attack, their tweets are not read. The company just updated its abuse policy to target those that attack others through the platform. The company also has a new tool to find abuse automatically by comparing patterns to previous patterns that were found to be abusive. The company also plans to be more responsive to reports of abuse.
This is a change from prior activity by the company which favored growth over limiting the actions of certain members. Investors are looking for growth in subscribers and the company has seen a decline in engagement recently. They now feel that by limiting the abusive accounts, they can increase engagement and hopefully membership.