Well, let me rephrase it then. If you aren't going to play until you hit 600 pearls, you shouldn't play the game at all. Obviously I can't guarantee the feature will pay anything, or have any knowledge of what the game's RTP is, or if it's functioning as it's supposed to, but the whole game is built around accumulating pearls for that feature.
As I've said above, that's why I usually avoid accumulator slots. You're either stuck playing the game until you hit the feature or you have to throw away what I built up.
If you have so little trust for the software provider that you feel like their games are just raking in your money hand over fist without any chance of paying out, you should probably not play their games. Personally, I do think the odds on RTG games are generally pretty terrible. They give you 200% bonuses but the games are incredibly difficult to actual win on, then if you do somehow win you might have your bonus eligibility restricted or other issues because apparently it's not supposed to actually be possible for a player to win.
I probably paid 7 or so RTG casinos total in the last year or so - of those, 4 of those I never won anything on. One I won and made me waste 6 months of time and effort to get paid (inetbet). Another I won a single time, had my eligibility for the larger bonuses removed (without word, the codes just don't work), ended up losing all those winnings back and more, and despite being down net still can't use the bigger bonuses (casino extreme - probably never going to play their again anyway, they have their games set to eat money.) The last one and only RTG casino I've come out ahead at is fairgo, hit a random jackpot there and they restricted my bonuses right after - don't play there much either now.
So as I said, it seems like RTG casinos really are not set up for players to have much chance to win, and they freak out if you actually do - even if you would have ultimately given that money back if they treated you better. It's unfortunate but Rival really probably is the best major provider available to US players, but there are only a few decent casinos with their games. There might be a couple other decent ones like endorphina but not many casinos offer them.