Um, no it's not. LAS to GCN is 169 miles which would take 1:28 at 100kts. You'd have to fly over 220kts to make that in 40 minutes which a tour helicoptor can not.

What he's probably talk about is a tour to 1G4 which in Canyon West Airport. LAS to 1G4 is 75 miles or 0:39 at 100kts. That is at the western-most end of the Grand Canyon where the canyon is significantly smaller than it is in the GCN area and where there is only a single canyon, not a canyon within a larger canyon. I'd recommend going all the way to GCN as you'll see a much large amount of the Grand Canyon, more than half of it, and you'll see a portion of the canyon where it is at it's largest.

Take an airplane tour from LAS to GCN then take a helicopter tour from GCN or Tusyan down into the canyon.