1.
Your "largest investor" excuse is a complete joke. First of all by just putting 90% of the funds in 1 address, you are not necessarily giving out information of this investor. Secondly, since you claim to still own more than 90% of the funds, you can simply move only your own funds to 1 cold address and this "big investor" is not even included(!!)
2. Investors have invested tens of thousands of bitcoins over the years (especially JD obv) and this is the first time I hear a ~30(?) coin investor having a concern about his privacy.
3. He isn't really a large investor, he must have less than 50 coins invested and there is 0% reason for you to be SO shady just because he tells you to do so.
4. If a player wins you will pay out (right?), so his coins will be transferred to that winner. Oops "privacy" gone.
5. Getting privacy for this situation is dead easy and cheap. Just deposit and withdraw from a known bitcoin exchange. Costs the investor 0.0002 BTC and few minutes of time.
Ugh, no need to argue anymore. Anyone who cannot see that this is a scam in the making is extremely naive. It is so easy and obvious to make a cold wallet address and your excuses are invalid.