If I tell you to go buy 10 apples, refusing would be insubordination because it's legal to buy apples.
If I tell you to go steal 10 apples, refusing would not be insubordination because it's legal to buy apples.
Until the court ruled against them, the view of the firm would have been it was legal to require someone to have their camera on. Hence they viewed it as insubordination to refuse.
They are wrong, it's not insubordination, but it's not unfair of them to think it was.
The employer was also found wrong by a court.