I can explain what is definitely not grooming: grooming is not something that would magically become okay after a parent consents to it and would be wrong before. Grooming is real and not something to be used as a boogeyman.
There is an age for children to learn everything. A 1 year old might be too young for Javascript. But calling it grooming is going way too far.
Grooming is wrong at any age, period. Even after the person is 100 years old and their parents signed on it, grooming is wrong. There's absolutely no "parental consent" that would turn anything that could be considered "grooming" into "appropriate". Your entire premise that something is grooming or not depending on parental consent is pure bullshit.
EDIT:
> I asked you what age do you think it's okay to teach these kids these lessons without the parents consent
Same thing. Parental consent is also not what makes certain information appropriate or inappropriate. It either is appropriate for the children or not. Depends on multiple factors and depends on the children, and it is better answered by professionals rather than by laymen. But it definitely doesn't depend on a parent agreeing or disagreeing.
> In my opinion talking to a minor about sex without parental consent is never appropriate.
That's quite a radical position, and a wrong one. There are appropriate ways for people to talk about sex, either in classroom, between friends, or in the media. If you don't think so, the only thing we can agree is to disagree.
Like the PG essay says, wether something is "truth" or not, and whether this information will be positive or negative for a child should be what govern this. Not some radical opinion of an helicopter parent that wants to micromanage every information their kid receives.
> I don't see why liberals are dying on this hill.
Because it accomplishes nothing but ignorance to children of conservative parents, which can lead to... children being more vulnerable to real grooming.
Comparing teaching to grooming and considering the two the same is a bad-faith argument.
Anything that could realistically be considered grooming would NEVER appropriate, even with your so called "parental consent". Even with adults.
Just because you call something "grooming" doesn't make it so.