I would imagine it could? But don't understand why a two year old might need it. I have a two year old and 4 and a half month old and don't have a use for it with either of them. I used it with them through their newborn stage.
I really don't think this could be of any help for your little guy in a big forward upright car seat. I know I feel horrible when my boy sleeps in the car seat and his head flops forward. I wish there was a way to keep that from happening.
I should specify that this is suitable for a baby who is in an infant car seat. With that said, if your sweet pea is in an infant carseat, it should serve it's purpose fine :)
Get one of those pillows that they use on planes for you neck. Those u shaped pillows. When your son falls asleep, put it upside down under his chin & neck, that should help his comfort alot so his chin won't flop to his chest