Replacing beef with more factory farmed chicken and pork is an ecological disaster.
Overall, pasture chicken requires a lot of land and has soil loading issues (too many and the soil gets burned out when the balance of minerals goes off kilter). It’s much harder to overload cows on pasture - it’s obvious when a field is overgrazed.
Pasture pigs are labour intensive, too.
The idea is to reduce meat overall, when I said "subsidize CO2 efficient foods", I was mostly talking about fruits, vegetables, grain, ... who reduce emissions and soil pollution by another order of magnitude compared to chicken and hogs. It also reduces antibiotics uses which is a plus.
Industrial scale grain farming also means heavy use of machinery which, again, all runs on fossil fuels. Whereas pasture raised cattle requires far less of these sort of inputs. A balanced approach to agriculture recognises the important of pasture animals such as ruminants and also recognises the damage excessive row crop farming causes.
Making it expensive so that consumption of specific types of food is expensive is the point. The more expensive, the less consumers are likely to consume that type of food.
This carbon tax can also be used to subsidize CO2 efficient foods, making them cheaper for the consumer in the end.