I mean... Yeah... Long ago some people got together and said large government organizations should not censor speech. They thought this idea was good enough that it shouldn't just be law, they should Amend the US Constitution to protect people from a particular large organization's overwhelming power to suppress dissent.

But today the organization censoring speech is a public corporation [wealthier and more powerful than most governments], and because it doesn't have explicit ties to any government, we are supposed to assume that the spirit of the original rule is not being violated. Citizens may expect no freedom of thought or expression, even if the properties Google owns appear to be and function like public forums.