If you try to run flutter as root, you get a message saying (my emphasis) "We strongly recommend running the flutter tool without superuser privileges."
https://github.com/flutter/flutter/blob/master/bin/flutter#L52

However, despite saying this is not recommended the script simply terminates. We should either allow this, or change the terminology to say it's not supported.