I don't think your criticism is entirely fair; for one, you can only compare OS X users to Windows users, which isn't at issue. Perhaps if you had a native version of your application the conversion rate would be 4x that of Windows. Furthermore, I would suggest that Bingo card applications have a different target audience than developer chat applications and that the former is less bothered by platform inconsistencies.
It was telling to me at the time that actual business results directly contrary to hypothesized outcomes identified in advance are treated as having no informational value with regards to the original claim.
So, your new working hypothesis is what, that Mac users secretly prefer Java UIs? That might prove too much.
I don't think it's a secret that Mac users are, by and large, more comfortable than Windows users at paying for and installing software. The paradox of choice is in less egregious effect, and they have fewer scars from past attempts.
