They were not YouTube-approved scientists, and DeSantis is not a YouTube-approved governor. As a private entity, Youtube is allowed to censor people they don't

They were not YouTube-approved scientists, and DeSantis is not a YouTube-approved governor. As a private entity, Youtube is allowed to censor people they don't like for any reason they wish. Just like they are allowed (and do) promote channels and Youtubers supportive of their political ideologies. Anyone who disagrees is free to start their own Youtube.