Could you explain the calculations that lead to the claim that the result is not significant? From what I can tell, if we assume that clicking the ad is a weighted binary variable, eg. what is modelled as a "proportional distribution" there's a statistically significant difference between the two results. It's even pretty strong at P=0.006 (per https://epitools.ausvet.com.au/ztesttwo), but I might be missing something?

In other words, if I'm doing the math right, for him to p-hack this by rerunning the experiment in the case of no difference, he'd have to run it more than 100 times to get a 50% chance of getting as good or better significance.

There's of course plenty of other things that could be wrong outside of the simple statistical test, he could be making the numbers up, the groups might not be properly randomized etc.