Vino was the one responding to the attack by AS. And Vino saw what happened to Andy's chain, and sat down.
AC blasted by as AS was looking at his chain and about to step off his bike. AS had slowed so much that AC had to quickly move to the left to get around the rapidly slowing AS.
There was no way that AC did not know that AS was having a mechanical.
+1. Vino had no problem recognizing the problem and sitting down & AC had a clear line of sight to AS the entire time. Can we please dispense with the "didn't see it" arguments? AC saw an opportunity and took it, plain and simple.