My mother-in-law is forcing a sick kitten to become a barn cat

I am an animal lover and plan to become a veterinarian technician, I have a special love for cats. Because of this, I have deep feelings of guilt and sadness when I see an animal being mistreated. Recently my sister in law found a sick kitten without a mother or siblings and took it to the vet planning on taking it somewhere to be fostered or adopted. I offered to adopt it myself as I am equipped with the knowledge to take care of a sick kitten and have other cats of my own. They then decided that they loved the kitten so much they wanted to keep him and named him Garth but they have 12 dogs that will attack the kitten on sight, so they decided to keep it outside in an area where their dogs wont be able to get to him. They have went on vacation and left me to take care of the dogs and I brought the kitten home with me as he is very loving and friendly and he gets along well with my kitten and puppy. I am feeling very sad about this as I am worried the kitten will not survive very long outside, he seems to have allergy issues which they have not yet taken him to a vet for. Am I being dramatic about this and should I just mind my business? If this is an ethical concern is there even anything I can do about it? I just feel awful for the little guy, he's laying in my arms right now purring away I can't imagine him trying to live outside in the woods.