A real pawrent would never leave a "sick" kitten outside in the cold.
How many times do we have to say that cats don't belong outside? Cats are meant for the comfy, cozy interior of your homes, where they can rule you like the servant you are. They are meant to choose to sleep on the wooden table instead of their purrfect plethora of plushy cat beds you buy for them. Sure, there are some instances where cats must be separated from others (for example, if one is sick), but usually that means isolating one in the bathroom while the others free-roam around the house. If an adult cat shouldn't be left outside to fend for itself, a 3-month-old kitten certainly shouldn't.
One feline family claimed to fostering a cute kitten, who they claimed got their other cats sick. They appawrently received "advice" to keep the cat outside, but one caring neighbor stepped in to save the poor kitten from a night out in the cold. The foster family agreed, and the neighbor and her new kitten happily stayed together in their heartwarming home. Then, a week later, the foster family basically accused the neighbor of stealing "their" cat, even though they were basically going to abandon it outside anyway.
Well, all that meowtters is that the kitten is with a family that loves it and it's safely inside and healthy. If they really wanted another kitten so badly, maybe they shouldn't have left their first one outside in the furst place!
source https://cheezburger.com/43886341/i-just-stole-a-kitten-caring-neighbor-rescues-3-month-old-kitten-left-out-in-the-cold-only-to-be