Children already spend too much time in front of computer screens. Introducing coding lessons at school just leads to more screen time.
Programming is active, staying in front of a screen is passive. They are not related.
The increase in time in front of computer screens that might come about from adding coding classes to the curriculum can be offset by cutting back on other forms of screen time.
Coding does not mean nor is it equal to screen time. Many unplugged activities can be used to teach the fundamentals of coding.