Your solution works! It’s not exploitable, and you get much more than 0 in expectation! Congrats!
Eliezer’s solution is better/optimal in the sense that it accepts with the highest probability a strategy can use without becoming exploitable. If offered 4⁄10, you accept with p=40%; the optimal solution accepts with p=83% (or slightly less than 5⁄6); if offered 1⁄10, it’s p=10% vs. p=55%. The other player’s payout is still maximized at 5, but everyone gets the payout a lot more often!
Your solution works! It’s not exploitable, and you get much more than 0 in expectation! Congrats!
Eliezer’s solution is better/optimal in the sense that it accepts with the highest probability a strategy can use without becoming exploitable. If offered 4⁄10, you accept with p=40%; the optimal solution accepts with p=83% (or slightly less than 5⁄6); if offered 1⁄10, it’s p=10% vs. p=55%. The other player’s payout is still maximized at 5, but everyone gets the payout a lot more often!