That’s a great point. I believe there are ways of handling this, but it will take some doing. For existing jobs, I was thinking that people would have the option of receiving their normal salary or the lifelong benefit, and that there would be new programs intended for people who opt-in to public works. Maybe you have companies with employees that are eligible for a salary or public works pay the salaries of public workers to the government (which uses it to fund the program) to disincentivize them from firing their non-free employees. Existing government jobs could also have a protected status, which triggers a regulatory structure that targets these incentives.
My responses here aren’t fully baked, but hopefully that starts to form the basis of a solution to the issues you raised.