In this case, the player violated this on their own accord. As right as this was, no surprise it made the business people unhappy. 'stronglikedan is correct in saying it's pretty much like misappropriation of company resources.
(In other news: entertainment is fake to the core. It's not about the game, it's about making money.)
But I also think it's 100% fair for the audience to be angry about this. It's a free market, and if people don't express their morality and/or politics through ways that impact the profits of the offenders, the market will not take those morals and politics into account. Bad press is a market signal too.
I mean, take your favorite sports/e-sports stream. How much political opinions does the streamer voice? Would you really recognize, from just watching the stream, if they were censored by the Chinese?
Just watching gameplay with no opinions and interaction is a watered down boring stream in my opinion. Maybe there are times when that is what someone wants when specifically looking for gameplay tips and how pros play, but that is only a subset of game streaming even by professional gamers. If the streamer is a sponsored pro, sure they have to worry about those sponsors but what kind of advice is it to tell them they should have no opinions? It feels short-sighted of the sponsors because they are limiting the potential of the stream and if they already sponsor someone, why wouldn't they want their opinions heard?