I can try to give you the most "good faith" argument in favor of allowing Blue States to go bankrupt.
There's a caveat here that the Federal laws will need to change a bit to allow States to go into packaged restructuring. And to ensure that we are bailing out specific individuals to ensure that they are not too negatively affected.
One of the strongest arguments against "bailouts" of large corporations is that it negatively impacts price discovery. More specifically, it removes a company's ability to thrive in certain extreme conditions from the pricing equation entirely. An example: Amazon is at all-time-highs right now, and it's because it's proven itself to be a hugely important institution, both during wartime and peacetime. Its market price should reflect this value. Airlines, OTOH, are an institution that can be prone to failure when some things go wrong (exogenous or otherwise), and the price should reflect that. A theoretical airline doing $1B in revenue should be worth less than a theoretical Amazon doing $1B in revenue, even if both have identical profits, growth, balance sheets, etc. The net effect of this is inefficient and poor capital allocation, where more capital would be allocated towards airlines than warranted, and that capital could be allocated elsewhere in more productive / less risky endeavors.
This may come across as overly fundamentalist about the market, but where this really manifests is in the Fed's bailout of junk bonds, which is absolutely nuts. The whole point of junk bonds (I.e. the type of a loan that WeWork would have to take) is that it's default risk is high, but the yield is also high. If junk bonds are bailed out, then that means that we all ought to go and buy junk bonds. High yields for everyone! The Fed is going to bail you out no matter what. This, then, overly inflates the demand (and price) for junk bonds, and you now have a total capital mis-allocation, with a lot of capital going into AirBNBs and WeWorks of the world, rather than the Amazons of the world.
How does this relate to States? Taxation is the price we pay to live in a society, and States are a really underrated way we can accurately come up with the correct "price" for the correct basket of services society might offer. This is the Charles Tiebout school of thought. Bailing out states with shitty fiscal policies is 1) a moral hazard and 2) messes with the long run calculation of the optimal level of taxation.
Okay great, so then what happens if we just let States "fail", like we might let Corporations fail? If we allowed States to declare bankruptcy, the bond-holders won't get paid, and the State credit ratings will shift to reflect their true creditworthiness. In this regard, bailing out bad States is no different from bailing out junk bonds — the only difference is that today State bond-holders don't know that they're holding onto junk bonds — most States have a generally high credit rating (except Illinois, because, well lol)[1]. The only mechanism we know of for the system to correct the ratings of these bonds is to 1) let States relieve themselves of their debt obligations, and 2) organically allow the bonds for those States to become more high-yield.
You might argue that this makes it difficult for States to fund infrastructure projects and safety nets. Yes, it makes it difficult to finance projects in the short run, because the bond failures are reflective of the quality of the current governance. Who comprises the government, who is running things can change democratically — if citizens want more infrastructure projects / better development, they will have to vote for better policies and better representatives. It's the democratic equivalent of swapping out the entire executive team at WeWork with the executive team at Amazon. The alternative is that you never see these governance changes at the State and local levels, and you have the same problems in perpetuity because the same people are always in power, and we never learn from mistakes — institutional rot. Better governance might be to restructure bad pension systems, or raise their own State taxes (IMO State taxes are far too low).
TL;DR — the best argument for letting States go bankrupt is that it's an effective way to weed out institutional rot in the long run, and come up with the optimal level of taxation for the optimal basket of State provided services. Such a scheme can only work if individuals continue to be bailed out so that they are not caught in the onslaught.
[1] https://en.wikipedia.org/wiki/List_of_U.S._states_by_credit_...