I know this is a necro troll thread, but two things stick out to me:

One, they keep referring to Indivisible only. It's like they don't realize that the bar is only the warning sign to pay attention to what the robot says next.

Two, I learned primes are numbers that are only divisible by 1 and itself. Just because "itself" is also 1 doesn't change matters. It's divisible by 1 and 1, hence, prime.