Too busy: what typically happens is that the concern of the spin-off of the disc business would be delegated to one / a few board members whose responsibility would be to examine the issue and make a recommendation to the rest of the board. The board member(s) themselves are rarely the people doing the analysis of the options; instead they delegate to salaried workers (either of Netflix, a contractor, or working directly for the board member) who do the legwork. So the amount of time that a board member themself will spend on the deal is either zero (they're not a member of the committee responsible for sourcing the recommendations) or fairly minimal.
Mistaken is another form of stupid.
And do you really think you get to be on the board of a ~$168 billion market cap public company by being stupid?
Boards of private companies or public companies with $168 billion market caps?
Private companies, sure. Boards of private companies often have an iron grip on shareholders and are often unaccountable. But the boards of public companies need to worry about shareholder activists, hostile takeovers, shareholder lawsuits. The margin of error to keep outright stupid, corrupt, nepotists is much smaller on large public company boards.
Mistaken is another form of stupid.
And do you really think you get to be on the board of a ~$168 billion market cap public company by being stupid?