Professional poker players who file taxes as self employed must pay self employment taxes which covers Social Security and Medicare. It doesn't cover unemployment insurance or compensation insurance (although they might get some disability insurance from SS in certain situations, I'm not sure), which are programs administered by the states. Hence, they will collect Social Security and Medicare if they make sufficient contributions over their lifetime. They will not collect unemployment insurance or state compensation insurance. They are free to take out a disability policy with a private company, but good luck trying to collect if you're not in the hospital for several weeks or bedridden. This is the first time they could have defined their situation as anything close to "unemployed", so there was little reason for such policies to be offered by insurance companies.
However, they might qualify for welfare in some areas if the problem persists.