It's also generally used in extremely low signal comments. For example, a person might talk on Twitter about how they think teachers putting up posters saying they support gay students is helpful. They'd then get tens of replies with only the exact phrase "Ok groomer".
The problem is, you seem to be intentionally misconstruing the definition of the word "hateful" in order to categorize words you don't like as "hate speech".
There is no other way that the thing you described meets any reasonable definition of "hate".
That's hateful. (I deliberely didn't say hate speech)
We aren’t talking about lectures extolling high marginal rates.
Some parents object to exposing children to inappropriate sexual themes for the purpose of conditioning them to accept the same as normal, i.e. grooming.
In the specific case of the use of "grooming," I can see how it is not obvious that this is hate speech, but once you connect the dots, based on the context, it becomes quite obvious.
For example, teaching books that feature any LGBTQ characters has been called "grooming." What is the usual definition of grooming? Preparing a child for sexual abuse, which is morally reprehensible -- a behavior that is, frankly, deserving of hate.
However, when the only reason "grooming" is brought up is specifically because a book feature a gay character, we are expected to "hate" the "morally reprehensible." Why is it morally reprehensible (hateful), in this context? Certainly not because children are being groomed for sexual abuse. The only reason is that the gay character is in the book.
Now, some people might think that presenting characters that are gay is morally reprehensible. They might think the same thing about featuring Black characters, Asians, Jews, or some other group. It's all hate speech. Even if it's not using the most blatantly obvious inflammatory language.
The only reason it's up for discussion is because it's being used as hate attack against queer communities and those standing up against censoring of teachers, students, and banning of books on lgbtq topics and gender.
The response of the proponents, which sadly seems politically effective, is to label anyone who objects to these laws groomers.
Implying/whistling that queer people exist because they were groomed, e.g. sexual predator turned them gay.
It is aimed at queer people.
* And ironically those of us who are standing up against, you guessed it.... free speech. *