This is terrible if it works.
Imagine if other employers want to join it. And then even more employers... and what if the scheme becomes so large and covering so much of the population that it ... gasp... looks almost like a government-run non-profit health insurance scheme! You know, like what those Marxists in Europe have.
And where it would it end - soon people would be demanding cheaper drug prices and being able to negotiate prices for drugs! Insane
(In case its not clear, the above is written ironicly. I am all for a well funded government-run health service)