Especially so for someone with some sort of seasonal income. They're the type of individuals who should know better than to not have a reasonable buffer (in case work doesn't come in that season).
I hadn't heard of income-protection insurance and after some googling it's no wonder: as far as I can it's a kind of disability insurance - it doesn't kick in if you're merely unemployed.
At that point, you're at the mercy of your state's unemployment insurance - which you might not be eligible for if you've been working as a contractor or self employed. Not to mention that seasonal work makes it harder to plan, since you don't have reliable income to plan around.
There just aren't that many "no-brainer" options for absorbing this many shocks, at a scale most individuals can cope with.
Pure private unemployment insurance.