I think it could be vegan even if the mother isn't vegan. We don't classify food animals as "even less suitable for vegans" if the animals ate animal products, right? It's just all not suitable. I realize the child would be getting some animal products through breast milk if the mother were not vegan, but it's hardly on par with the baby drinking cow milk or eating eggs.
Q: How many poets does it take to change a light bulb? A: 1001...one to change the bulb, 1000 to say it's already been done.