Yep this is the problem with most of the streamers nowadays. They can't let go of the sponsorships of the casino and they shill it on their stream. There might be a chance that streams aren't scripted but if they are paid to stream the brand, They are most likely be promoting it at their own will given that they want to take another chance by being sponsored again and gain money of course. At least they are some streamers that are entertaining to watch to even we know if it is scripted.
I don't think that the streams are scripted and I have no problem to watch streams of sponsored players if they announce in the beginning of the video that they are getting sponsored. It is more shady if they don't mention it but when you research it and find out that they are also sponsored, than it all stops for me.
It could be scripted. After all, we will never know and just enjoy the spectacle from the streamers. And if I watch the video from that streamer, I feel a bit jealous of them for being able to win the game with an amount I could never have imagined. But then again, I'm just a small player who can only dream that one day I can win a big amount, even though it's not as big as the streamers.