Yes, we've worked a lot on detecting such manipulation.
I looked into whether it was employees doing the flagging, but I didn't include that in the GP because I can't tell for sure who was or wasn't an employee. What I did find is that of the flaggers, most haven't ever voted for a stripe.com submission (before or since). There were two flaggers who have voted for quite a few stripe.com submissions, but not enough to trigger any manipulation detectors. They both had voted for many thousands of submissions over many years, so I didn't find any evidence of abuse. In the case of one of those two users, there is a bio in the profile which makes it seem unlikely that they worked for Stripe. In the case of the other one, I don't have any info.
FWIW, looking at the flagging data on that post pattern-matched to 'normal' in my brain, not to 'suspicious'. I realize that won't (and shouldn't) carry any weight for users who aren't already inclined to trust what I'm saying, but (a) we do have a ton of experience looking at suspicious voting and flagging patterns, and (b) it's true, so I figure I might as well say it.
Edit: I just thought of another way to investigate this, which I overlooked earlier: I looked at everything else that those users had flagged. That was easy enough, because none of them has flagged more than a few dozen submissions over the years. There were no other cases of people flagging Stripe-related submissions, except for this one, which was a pro-Stripe story:
Stripe has democratised online payments and reshaped the digital economy - https://news.ycombinator.com/item?id=18153909 - Oct 2018 (43 comments)