Yeah, a sideline warning comes with a flag thrown and the referee announcement and everything. It’s not a private warning from the officials to the bench, they let everybody know.
I suppose it’s allowed to jump to the unsportsmanlike penalty without a warning, if it’s an obvious and egregious violation, but jeez … I don’t recall ever seeing that, you usually get a warning before you’re actually penalized, and seemingly recovering a fumble to ensure a victory ought to give that team a little leeway for sideline excitement. It was a truly head-scratching call.