Most likely, he did things like look around into corners, pay obvious attention to exits and places where people could hide, or set up an ambush.
The security people at Disney know where all of these places are, and then some, and can no doubt tell when someone is showing undue interest in them.
Kind of like when your wife can tell you’re paying undue attention to that blonde at the other table. :P
“Blonde at the other table”
Best post of the day
Or he tested their security with “it’s just a clock” and they recognized his BS