Or he's trying to get extra money for the family...? Are you able to have a relative/friend help you with your DD on that day?
FI works 12 and 24 hour shifts all the time, and will continue to do so, even well into overtime. While I really wish that he were home, the extra money goes directly into savings for baby related things, especially hospital bills that is left over from insurance.
He is working on that day, just not for the 12 hours he was planning, more like 10. The reality is, we love that paycheck after the holiday season, and regardless of our daughter's birth, he plans on working through the 5th for the bonus pay. It is, however, very possible that we will be in the hospital for a birth right before that day. This could equal out to a day old baby and a lonely recovering mommy in a hospital while daddy is working away. Let's face it, that would suck for anyone, him included. I am very supportive of his job as it is what allows me to be a SAHM year round (I am incredibly thankful), and he really loves his job thus making for a happy hubby.
Lord knows that I do have a supportive family, and no doubt they would do the best they could to help out, but I just can't make it my family's responsibility to cater to my needs post birth when my husband is capable and willing, but wanting a larger paycheck. Thankfully we have amazing insurance through DH's work, and won't have a bill afterward, and financially we are doing well so this is really more of a "wish" than a requirement.