I say that 50% takeover reduction when the game reads a 1v1/2v1(someone disconnects), while anything above that has the lock count as one demigod, is a possible solution.
It just requires some extra coding to switch the effect of the lock over when it goes from 2v2 to 2v1. You might say "oh that one person is screwed anyway, why bother," But lets say someone on the other side leaves to balance things and its 1v1.
You might not think that happens alot but in DotA you could set up a 2v2 game and two people might leave immediately.