The recipient may have filtering turned on that would reject the automatic reply;
Sure, Kopelman is truthful about the fact that he's on vacation, but he also lets the recipient know that he or she would be interrupting important family time if the first option is chosen. It states a point simply and uses humor to avoid making it sound like he wants the reader to feel guilty.

In 2013, researcher danah boyd wrote a LinkedIn blog post advocating for the nuclear option which was framed in the piece as an “email sabbatical.” Coming back to an empty inbox after a vacation is should be a break from the insanity, not a procrastination of it,” boyd wrote of the decision to send everything to the trash.
I used to work with someone who had a message telling people she only checked her email twice a day. You pretty much needed to call her if you needed anything outside of those times. (She worked in a remote office.) I think she had read one of those books on efficiency that recommended scheduled email time. But there were problems with this: 4. My department often had to email attachments or text to illustrate our questions/concerns. And we were on deadlines. Reading a page of text over the phone was not an efficient use of anyone’s time 5. She did outreach & was often out of the office on site visits, trainings, or travel to these places, but never ever set her OOO for these, because she was “working.” However, she was effectively not available to read emails from other staff until after hours on those days.