It makes sense if you remember that the universal healthcare system is insurance.
So if you are trying to migrate without a job but with an expensive disabillity and little money, then you are just a liabillity to the healthcare system.
And since the country is under no obligation to pay for the care, there is no reason for them to do so.
It is just basic resource management, you may not like it, but it is reality, regardless of what political system the country uses.