I think it's the right thing to do?
My cousin's wife is 17 and just had a baby (she's a first time mom, and I know her parents basically disowned her, so she isn't getting motherly advice).
Today, she posts a picture on FB of the baby sleeping on a pillow in their bed by herself with the bed's big blanket laid over her, up to her neck. The mom was saying she was spoiled and so comfy napping like that, but by brain is seeing huge SIDS risks everywhere. ETA: the baby does have a crib of her own.
Would it be awful of me to send her a message (I barely know her!) saying, "I'm sure you know this, but it's much safer to let baby sleep in her crib without the fluffy pillow or blanket. It seems comfy to us, but those things can be big SIDS risks for newborns. Baby is soooo cute; I can't wait to meet her!"