Yeah, that's what I thought too. Not clear at all. Still wonder why the "bronze" plan seems to be such a clear winner. IMHO, insurance is never about good choices for the insured and is always about what's best for the insurance company. That's what makes me nervous. OP - please be very skeptical and very careful before making a choice. Dig deep and ask questions.
The rates for the bronze plan are likely much higher than $350/mo, but the employer is subsidizing a large part of the premium if the retiree chooses that plan instead of the gold or silver. Employers are not required to contribute anything to retiree benefits, so that is their way of rewarding employees, while pushing them away from the cadillac policies that drive up rates for everybody.