Twitter already does hide NSFW ("objectionable") content behind a click, removing it only when it violates the platform rules of conduct.

They evaluated and rejected hiding "violates Twitter policies" content except in the rare cases where they deem it necessary for the public interest to retain that violating content behind a click barrier.

https://help.twitter.com/en/safety-and-security/offensive-tw... has more details about the current policy, and you can read their blog posts from the past couple years about these policies to gain more context and background.