One would assume that airlines requiring a bailout are financially marginal, and unable to survive without nationalization, while airlines not requiring a bailout would be in a financial position to weather the temporary black swan event causing the need for bailouts in the first place (for example American Airlines might require a bailout, but Southwest likely will not).
If every airline needs a bailout, you might have to evaluate a program of greater scale; injecting cash directly into every airline in a coordinated effort, but taking equity and putting in place governance (with a board seat or more than one) in those needing the bailout. Those who won't accept such terms would be permitted to fail.
My apologies it's not a binary answer, and more "it depends."