As opposed to chess, magic is about lying and cheating. Everybody knows it and everybody is fine with it in magic, as you can see here in Dary's legendary ambitious card routine:
Nonetheless there's a rough ranking of "acceptable lies", and a thumper - anything with a secretly complicit audience member, really - ranks near the bottom of that.
https://youtu.be/w4iu5FMaR2o?t=71
Edit: At the grand finale at 7:51 he says it again: "I haven't cheated yet, but it's coming up."