My understanding is that Horiuchi was a mere sniper at Ruby Ridge, and the FBI was so pleased with his performance there that they promoted him to sniper team lead at Waco, i.e. embodying the quintessential skills they were (and are still) looking for, namely murdering US citizens in cold blood.
It’s been awhile since I have looked at Waco. I have rules of engagement and the 2 follow-on films, at least on VHS.