I thought it was cute and could tell that the person writing it probably spent a lot of time on the road and needed a shorthand for updating their message.
This would go over like a lead balloon at my company, and, were that person on my team, I’d tell them to change it. It does have a connotation of “when I feel like it” about it, and most of my team is not high enough up the food chain to take that sort of stance (and the ones who are high enough up are client-facing and have the good sense not to do so).

This is true! The nuclear option also helps the recently returned vacationer understand what is a priority and what isn’t. But, as boyd wrote, “if you just turn off your email with no warning, you're bound to piss off your friends, family, colleagues, and clients.” The blog post offers some helpful steps to make a clean break feasible — they include communicating with colleagues about the sabbatical long in advance, managing expectations of those who rely on you, creating a backdoor for true emergencies, and then, right before going away, reminding everyone about the sabbatical once again.
My husband’s voice mails says “…if you need immediate assistance call Mary at ####…”, only Mary retired something like eight years ago. I mention this to him every once in a while. It hasn’t changed.