I fully agree that staking should be diversified across different providers. With regards to liquid staking in particular, StakeWise should be considered as a great option for diversification. StakeWise can facilitate unstaking of over 10kETH currently and that is about to increase with new liquidity pools coming imminently.
The dual token model would also offer a decent boost to staking yields over and above both RPL and Lido, which could be meaningful given the amounts Olympus will be staking.