As a solution to mutator bred reapers not being claimable, would it be possible for a new type of pulse which changes a baby reapers birther parameter to whoever initiated the pulse or even just whose closest to the reaper? I havent looked too deeply into the devkit but surely it's just a matter of substituting in the correct value in for making the baby claimable.

In terms of balance I think even the base game has gone way beyond being balanced in that regard but mutator functions can be disabled individually anyway on servers that dont want it as far as I'm aware.