"Blame the hippies!"
I can't support what this politician is doing. It's understandable that there should be punishment for parents that are intentionally malnourishing their children, since this puts unnecessary strain on the healthcare system that everyone pays into. But it's not fair to point a finger specifically at vegans and vegetarians, as a poorly-managed carnivorous diet can also be severely lacking in nutrients. Very few people would make the claim that eating at McDonalds is essential to a healthy diet, even if they do offer salads these days.
Historically vegans have been known to take vitamin and mineral supplements to work around dietary restrictions. Why can't the government just mandate the use of supplements instead of outright banning niche diets?
This is yet another wedge issue, and it's partly being fueled by fears from the current world immigration crisis. Lots of immigrants from the Middle East, India, and ex-Soviet countries are bringing new dietary restrictions based on moral or religious philosophy, and the old guard in Italy can't bear the notion that they would need to be more accommodating to these immigrants, especially if it means fewer profits for Italy's meat and dairy industries. You can find a similar scenario in every country experiencing the influx of immigrants.