Freedom of Speech? Trump is banned from most Platforms.

Don't be fooled, you only are able to use those platforms at the discretion of the owner. Twitter blocking Trump is not a violation of free speech.

Trump can say what he wishes, and so can Jack Dorsey, each with their own property.

Trump has no right to shout from Dorsey's platform any more than Dorsey has the right to shout from the balcony of Trump tower.