I think the best way is don't let these people interfere with the MRT operations, if somebody jumped off, then let the MRT train move then afterwards remove his/her body
If there is not enough time to get all the body parts because another train is coming, then let the train pass then afterwards continue picking up his/her body parts
It may be rude, but it's no use to disrupt the MRT operations just to get the pieces of the man who in the first place did it to himself.
It's better for them to jump off HDB flats since no one will be disrupted to whatever they try to do to themselves.