1. Question: If what a mourner during shiva can and can’t do for work is based on what one can and can’t do on chol hamoed then why is he allowed to have a non-Jew do work for him if he is a mourner which will otherwise be lost but a Jew cannot have a non-Jew do work for him which will otherwise be lost on chol hamoed?
A. The Shulchan Aruch (Yoreh Deah 380:5) says it is forbidden for a mourner to do any work through someone else even a non-Jew unless it is something which will be lost which is permitted to be done through others, even if it is forbidden to be done on chol hamoed because it is too much of a hassle, it is still permitted for a mourner and even if it is something of craftmanship.
B. A mourner should not be doing any work in order to focus on the loss of his loved one.
C. The Taz (4) says that on Chol hamoed it is forbidden for others to do things which are a hassle, for you because of the honor of the holiday.
Answer: The honor of the holiday will be desecrated whether done by you or someone else since you are showing your work is more important than the day. But by the mourner the honor towards the dead is solely on the mourner which he has to focus on so it makes no difference if people are doing things for him, it allows his focus to be on his lost relative.