Stone spent a lot of time in Cuba. Honored guest of their government.
I certainly hope he learned the truth from the visit.
Castro liked Stone’s films, so he gave him unprecedented access and freedom to do a documentary. Backlash forced him to go back and reshoot, also with Castro’s approval.
It’s certainly reasonable that some people are skeptical or critical of Stone’s decision to do this, but I don’t think it supports the idea of Stone being supportive of Communism or similar ideologies.