It's usually not a problem for a business to incur a short term operating loss.
It's not quite as simple as cash-on-hand, turnover, or profitability. Start-ups without revenues or net profits may be solvent if investment capital is available, premised on future profitability or a viable exit strategy. But it's fairly strongly related.
Airworthiness is more an overall assessment of risk.
A substantially compromised aircraft, with expert piloting and favourable weather, can still land successfully.
A fully-airworthy aircraft experiencing CFIT won't. Nor will one flown into unanticipated adverse conditions such as violent weather, volcanic ash, or wind shear.
And of course, a sufficiently crippled craft cannot be landed successfully no matter what.
(An additional case is of a landing with partial survival of passengers and crew. We'll omit that.)
Airworthiness increases he probability of a successful flight. It's neither strictly necessary, nor sufficient. It is part of the overall risk assessment, effectively a creditworthiness rating.
An airworthiness certificate is a specific certification of such airworthiness.
Failure to maintain altitude above ground level and failure to maintain solvency are in many ways equivalent.
Both domains involve taking risks, but with severe consequences when either risks are miscalculated or ground truths change. Financial bets can be hedged in ways flight profiles often cannot be, and Southwest are credited for doing this (with fuel purchase futures notably), but there's a sense in which businesses are arbitraging latent risks for present profits in ways which can prove catastrophic. (Venture start-ups are particularly prone to this IMO.)
Southwest's single-airframe fleet affords efficiencies, but also risks should faults arise with that airframe or subsystems of it (as with the 737 MAX scenario).