The European Union Digital Markets Act, coming into effect in May 2023, explicitly forbids such behavior. (If twitter is classified as a "gatekeeper".)
Example of the “don'ts” - Gatekeeper platforms may no longer:
- treat services and products offered by the gatekeeper itself more favourably in ranking than similar services or products offered by third parties on the gatekeeper's platform
- prevent consumers from linking up to businesses outside their platforms
https://commission.europa.eu/strategy-and-policy/priorities-...
Example of the “don'ts” - Gatekeeper platforms may no longer:
- treat services and products offered by the gatekeeper itself more favourably in ranking than similar services or products offered by third parties on the gatekeeper's platform
- prevent consumers from linking up to businesses outside their platforms