...As I said, the company will be paying severance to these people for a while, so they won't be left out in the cold at Christmas. The law requires them to also receive healthcare for at least a year. It sounds like some of them qualify for Medicare.
First, nobody qualifies for Medicare unless and until they've hit age 65.
Second, "The law" doesn't require that the laid-off employees of any company "receive healthcare for at least a year." Even in employee-friendly California. (Relative to some other states, which can be overtly employer-friendly and employee-hostile.)
What you are referring to is
COBRA. That does require companies that lay employees off to offer them the chance to
buy a continuation of healthcare benefits (hence the "COB" in COBRA). The former employee must
pay for their coverage out-of-pocket for up to 18 months, at a cost not to exceed 102% of the employer's cost to provide coverage to continuing employees. (The extra 2% is to theoretically cover the employer's cost to administer the COBRA program. Also note that an employer who doesn't offer benefits in the first place has no obligation to offer COBRA, since there are no benefits to continue.)
So while the former employees get the advantage of being able to bridge their benefits at the employer's below-market-rate negotiated cost of providing those benefits to their "group", each employee must adhere to the law and the former employer's regulations, such as paying their premiums to the company by the first day of each month, etc. It's by no means a freebie, unless the company must honor the terms of a personal services contract or a union contract which require more than the legal minimum.
For any California employee who still doesn't have a job by the end of the 18 months, there is a state-level version of COBRA (CAL-COBRA?) that can extend the arrangement for an additional 18 months. If the employee is still unemployed after three full years and exhausts both COBRA and CAL-COBRA protections, the employee either transitions to the Affordable Care Act, i.e. "Obamacare", or has become old enough to qualify for Medicare.