The same as who is paying for PLEXed Omega accounts, CCP. All accounts cost CCP the same amount in overhead, dev costs, and server load. And CCP pays for that. They sell some of that cost directly as a subscription, and for the rest they provide “free” accounts, that they pay for to create an in-game market that drives “wallet warriors” to buy PLEX, on which they make money (the buying of PLEX for real world money, nothing that happens to the PLEX after that).
Regarding the bankruptcy example: it isn’t a matter if you will get anything, it’s a matter of what is or is not legal. The EULA can restrict refunds regarding people not wanting to play anymore, or an account being banned, but it is worthless if the company goes bankrupt and can no longer provide the service. Yes, subscription refunds would most likely come last, and not pay out anything, but they would have to be legally dismissed by a bankruptcy court.
Here you get it. 
Accounting 101:
Assets - Liabilities = Equity
Everything that is money, currency, or “paying” can fit into that equation, if it doesn’t fit in there it isn’t money, currency, or “paying”. (I’m not saying everything in the equation is one of those three.) For those who are arguing that “time is money”, despite the common saying the “time” you work will never show up on any accounting statement, ever. (Salary will, but that is the payment for time, not the time itself.)
When CCP sells a subscription (for more than a month) the money paid is an asset, but there also has to be a liability for the extra months as “deferred income”. You can think of it as a legal I.O.U. They can’t claim that money yet because they haven’t earned it yet, and if they never deliver that product or service, they will legally owe a refund.
Now let’s look at a PLEX: When CCP sells PLEX, once the PLEX is in-game, they don’t owe anyone anything, they could say “PLEX can no longer be used for Omega upgrades” and other than losing all of their players, they wouldn’t legally owe anyone anything. In-game PLEX does not create a liability, because it’s already completed its real world transaction.
I don’t think this is true, and I’ll address it more regarding the financials you linked.
I think the author of the post has made a wrong assumption. I don’t think “In-game purchases not yet consumed” refers to in-game PLEX, I think it would refer to ETC, MTC, and PLEX activation codes, these are un-redeemed items, which would cause a real world liability. Once PLEX becomes an in-game item it has been redeemed. Of course in accounting you can makes a lot of things show in a way that it’s really the truth of the situation, so they could have been showing PLEX as deferred income.
Here is the main reason that fictional in-game money/currency/commodities don’t actually have real world value (even though they can have a real world cost): because Eve players aren’t being arrested! If 500 PLEX is $20, and you take it from me against my will, that is a criminal offense. I know you might say that by playing the game I consented to losing my PLEX, but if that were the case Eve would have to carry warnings/consents like gambling sites do. If ISK or PLEX has a real world money value, then CCP would have to issue tax statements to all the players so they could pay taxes on their in-game earnings. None of that happens in the real world, because fictional in-game currency is just that, fictional. And being fictional CCP can’t pay in PLEX to keep the devs paid and servers running.