You (and your friends if they are real) are propaganda victims.
Here you will see that the FBI counter terrorism team was spurred by that Oct 4 letter to start tracking potential threats that concerned parents posed. So no, he didn't technically call them terrorists, he just had the counter-terrorism team activated to look for terrorists.
The NBSA sent a letter to the DOJ asking them to look into school board meetings around the country, saying that the parent protests were "equivalent to a form of domestic terrorism."
The NBSA has since apologized and removed the letter from their website.
Politifact responds by saying the word "terrorist" does not appear in the memo, thus the "domestic terrorist" claim is false. They created a straw man and then defeated it. Yeesh.
That's what Garland said per your article. The only ones who mentioned terrorism was the NSBA and they didn't accuse anyone of it, they suggested some of the threats they'd received could be equivalent to terrorism. So, no Polifact is exactly correct here and the NY Post agrees.
