PRO:
Speaking from a purely economic perspective (culturally we conflate money with morality), homeless people and prisoners cost the state roughly $20,000.00 per person per year. School children in the USA receive a subsidy of roughly $15,000.00 per child per year. Homeless people & prisoners & school children are unproductive members of society (jobless). It would be a great boost to the economy (culturally we conflate money with morality) if we found some jobs for these individuals (since we also tend to conflate laziness with immorality).
Of course a "jobs guarantee" probably doesn't mean "mandatory labor camps".
CON:
Speaking from a purely economic perspective (culturally we conflate money with morality), a deep, primal fear of becoming homeless and a deep, primal fear of being sent to prison contributes immensely to economic productivity. This fundamental and essential primal fear is what keeps the working class (80% of the country) going to jobs they hate, overlooking safety violations, taking verbal abuse from customers and managers, and accepting extremely low wages (keeping consumer prices competitive).
If these workers were "guaranteed a job", then they would walk away from these wretched, dead-end, often physically dangerous jobs and the nation's entrepreneurs would go out of business. These businesses would probably be replaced by government-run replacements because the government would have a huge surplus of employees due to their "jobs guarantee". This would lead to a totalitarian state, and everybody knows that totalitarian state = teh evil.
Therefore, "The United States ought to institute a federal jobs guarantee" = "totalitarian state" = evil.