Illiquid just means that you can't cash it in quickly.
Cash is 100% liquid while a house is illiquid you might have millions US$ parked there but only if you manage to sell it, then you convert it into liquid cash.
Liquidity is a measure of how easy it'd be to trade a thing for another thing you want.
Agreed, but in this case these tokens have suddenly become 'illiquid' because they have just become worthless. It seems that here the term 'illiquid' is being used as a euphemism.
Cash is 100% liquid while a house is illiquid you might have millions US$ parked there but only if you manage to sell it, then you convert it into liquid cash.
Liquidity is a measure of how easy it'd be to trade a thing for another thing you want.