It's a pointless line of argument to follow, no one is going to find a feeding tube sufficient cause for euthanasia.
But for explanation, I'll elaborate. A person in that state may, if fed normally, choke. The risk is higher than in a completely healthy person. However, this does not mean that every time she is fed, she will choke; it just means that the probability is too high for the feeders to accept the liability that might result if she does choke.
Your reasoning is completely opposite to my experiences in working with nursing homes and hospitals. I have never seen any facility refuse to pursue speech therapy (they do the swallow evals and treatments) for fear of liability. In fact usually it's the opposite, they try even with patients where there's not much hope. As I said, it would take a tremendous conspiracy to deny someone with the ability to swallow an attempt to feed orally.