I know this example has been allowed in the past to continue to be a three wire per AHJ.
And it is a hardship to the owner.
But code is code.
Besides as a AHJ you have the right to interpret the nec.
But I also see it as a problem in the future.
Dealing with this contractor and others on the next job.
This is the exact same situation and you let me do it the last time
Even if it really is not the same situation.
So it may not be a popular decision to strictly adhere to the code but it is the correct and consistent one.
HINT: I don't remember the person prior in your seat allowing it either.