What you need to understand is, the real reason they're upset about this is that they're seeing the clear signs that the long time Leftist Control of our education system is being wrenched away from them. The Right is finally, after decades of increasing Leftist Indoctrination of our children, starting to fight back and wrestle control over the education system away from these sick monsters. It boils down to this statement...

"The Left doesn't have children, they have yours."

Leftists are less likely to have kids, so for their ideas to persist, they need to indoctrinate others. And what better time to sow the sickly seeds of Socialism into someone than when they're young? Like King Solomon once said, "Train up a child in the way they should go, and when they're older they will never stray from it." What this law is, is a flashing red warning sign that their access and ability to poison kids minds with their regressive and failed ideas is being ripped away from them.

Just look at the anti-CRT pushes happening across the country right now. Glenn Youngkin in Virginia ran on an anti-CRT platform and won! Florida's Anti-Grooming Law has majority support across the nation. The Right is taking back control of the education system, and without young minds to indoctrinate and subvert to their failed ideology, their ideas will be all the more harder to push through in the mainstream. That is why the Left are losing their minds over the anti-grooming law.

That, and the pedophiles among them are going to find it harder to groom their victims now without detection.