Privately-held company. Food industry is generally not a high-margin business. Bankruptcy wipes out the common shareholders anyway. Not saying the shareholders never got any dividends, but I doubt if it was enough to have made a difference with the sort of pension obligation that they have.
Company pensions funded through the company itself or paid by the company and administered by the union (which seems to be the case here), as opposed to being operated independently by an insurance or investment company, don't seem like a good idea. Too vulnerable to things going wrong, either with the company or with the union.
Just wait, because there is another shakeout on the horizon for ex auto workers. The "detroit 3" have divested themselves of their pension obligations and handed it off to the UAW, but the UAW has a fraction as many dues-paying members as it did in years past, has practically no chance of organizing any of the import brands, owns shares in the very same companies that it represents but the value of these shares nowhere near offsets the pension obligation (and this places them in a rather interesting position, too), but is trying to operate as it did in years past. I would say that there is a significant possibility of the UAW going bankrupt because of this ... a situation that I have a hard time imagining that they could ever recover from. Bye-bye, pensions, for ex auto workers in USA.
Too-rich pension promises come back to bite later on. It's best when planning one's retirement that any company pension plan will be worth nothing.