When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction to that of the first body. So each will have the same momentum, whatever their mass. Consider what that means regarding the velocity of each. You might discover that they will come to rest at the same time.

the feces will come to rest first.

because it is less massive.

they will not come to rest at the same time.

the momentum will be the same even when there are two different sized masses involved.

because P=mv

the force that the monkey provides to accelerate the feces
will not accelerate the monkey as fast as the feces.
because the monkey has more mass than the feces.

because F=ma

the mutual force of gravity that is felt between the two masses
will bring them together at some point in time , the monkey will not stop first however , the feces will stop first then
begin to accelerate towards the monkey.

if the distance is great enough then at some point in time the monkey will stop and then accelerate towards the feces.

that's all basic physics , and I cant speak for orac but I think you already know this.

everybody makes mistakes.

3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science.