Can the commerce clause of the constitution allow the federal government to operate a public option for health insurance?
So you're asking whether the commerce clause could be construed to authorize the federal government to run its own Medicare-type program except not just for seniors?
I don't think that the commerce clause has been used to justify actual direct government actions of this sort. Since it provides the power to "regulate commerce" it has been used to justify regulations (like antidiscrimination stuff), not government programs.
Government programs tend to be justified under the "necessary and proper" clause, which states that the government can do whatever is "necessary and proper for carrying into execution" its other powers (like providing for the general welfare).
A thought occurs... are you referring to whether the government can mandate that people must have health insurance? Because that would be more of a regulation. If that's what you're asking, check out the link I've provided. As long as what the government is mandating is something that has a "substantial effect" on interstate commerce, it's fair game. And medical insurance and health care in general would seem to me to qualify easily under that rule.
Does that answer what you're asking? If not, ask again...