Totally agree with the core thoughts you have mentioned. The core observation I want to point out is that the LP incentive purpose in making it more attractive to ETH holders and less attractive to stETH holders. If the LP total APR goes much higher than stETH staking APR, it will make more stETH join the pool as LP and dilute the increase of joined ETH.
Even considering the discount(2.5% currently) and assuming the withdraw will be enable in 1 year, a 6% LP total APR will significantly attract more stETH joining the pool.
https://docs.google.com/spreadsheets/d/11Z-3GGkIfsFT1ZDXi87K-SsCTnyXSbupYxBWbS6ik5g/edit#gid=0
Glad to know more about your thoughts on this matter.