Right, because people looking through their cameras at all of the chaos, flashing lights and pulsating wristbands would _definitely_ notice one human being standing there with an IR transmitter and be able to understand what they were looking at.
I think at least a few photography nerds would notice the 30W white blob coming from where you're standing. Now whether that would get you in trouble...
They already have an even more powerful IR spotlight sweeping over the stadium; if that isn't ruining the photos, then I doubt the attacker's 30W source would even register.
Can confirm that everyone there is taking shitloads of photos and videos with their phones and I've never seen the stadium IR emitter appear in any of them.