I guess they are qualified to join but not to win because it might not be fair to the other players if they will wage the sponsorship coin given to them but instead it's good to gain more viewers if they might participate right more ideal. Unless they will use their main account or main money and have the authorization of the organisation to be part of the event.
If so, players with a sponsorship should generally be excluded from all competitions. It doesn't make much sense to allow them: Imagine a wagering contest where a player with coins from the sponsorship is allowed to play (and will win with a high probability) but is not allowed to receive the price for the first place. Sounds very fishy ...
In other contests where, for example, the aim is to roll a certain number (various Dice sites had this type of contest "back then"), it is also unfair, because you can simply be more careless with coins from the sponsorship and play much more often, but the chances of winning are correspondingly smaller.
I am not 100% sure about this. I mean yes they are getting paid to play at certain places and that is why they get money from the casino and that means that we are talking about free entry type of deal for them.
However, they could also gamble with that money without competition and still lose that money if they have a bad luck. It means they are gambling just like any other person. Their income is not the money they are given by the casino, their income is mainly what they make from streaming. This means they could be considered gambling just all of us, we find the money from other places, whereas they find it from casino itself, however afterwards is all equal.
