I do like the warning. Important because of the consumption of chicken eggs and meat. The explanations are good too.
But in my opinion: Chickens should not be given antibiotics unless it is clearly a bacteria that couses the sickness and is a threat to the flock. If you or the vet has any doubt on the sickness, its often useless to give antibiotics. The chicken will die or get better anyway.
Giving chickens enough space and a healty and fresh environment prevents sickness.
The abundant use of antibiotics in hobbying and farming couses health problems for people. An increasng number of bacteria are resistent for all antibiotics. Hospitals, dokters and nursing staff (at least in Europe) have a lot of issues with this.
Farmers and people who work with live stock have more often resistant and dangerous bacteria as other people have.
This is excellent information about the uses and nature of many antibiotics as used in DOGS. There is a good warning about using them (or not) on poultry, but it should also carry a warning that antibiotics must be used VERY carefully. If the user doesn't know what they're doing with them, a vet should be consulted about dosage and side effects.