There's no way for the dog to know the difference between his stuffed toy and your child's stuffed toy, once you start using a particular toy anything that resembles it is fair game.
I don't think you need to stop doing this, but that's where making sure your child's toys are picked up (or in a room where the dog(s) don't go), keep an eye on them, etc is important. And where teaching your child that we only throw dog toys for the dogs and not our cars trucks, etc as your child WILL be capable of learning that. Your child can learn that certain toys are for the dog and certain toys are for him even if that thinking isn't reciprocated by the dogs.
You may want to start associating a word with your dogs that indicates it's play time, something maybe in another language or an obscure word that isn't typically used. This way if your child happens to throw a toy the dog *shouldn't* go after it until he/she hears the word which indicates it is playtime. This will obviously require quite a bit of time and training on both your part as well as the dog's part.
I would say all in all it is NOT true, as your child will be capable of learning first that we don't throw toys AT the dogs, but away from them FOR them to jump after so there should never be a reason to throw a toy AT the dogs, secondly neither of them shoudl be left alone together for ANY reason so that's where parenting time comes in so your child understands what is okay and what isn't (let's face it your child WILL throw the toy at the dogs regardless of this game or not and WILL throw his toys at another child at some point regardless of if he sees someone else do it or not, it's just what happens with kids).
IMO it's how you deal with the situation once it arises that is the important things. You will eventually teach your child the correct way to play with the dogs and your dogs will be trained to respect your child. So, I wouldn't be too concerned until there's a reason to be concerned, which if you go about things right over the next couple of years really shouldn't ever come to a concern.
Good luck!