As someone who recently worked in game dev I'm not sure why 32 bit was even a factor as 64 bit is likely your default target anyway - has been for awhile. So, killing 32 bit is not a real issue.
Notorizing can be seen as just another cost of targeting a platform. So do it. You will need at least one machine anyway to do basic testing on. So use that. Get the cheapest imac or whatever you require. So, mac hardware isn't a real issue.
I found the statistics a bit strange as well. Sales were 2% linux, 4% mac, 94% windows. Yet support was divided 30% linux, 50% mac and 20% windows. This suggests linux is more problematic per sale than mac. Yet he has no issue with linux. If this was me, I'd be wanting to know exactly why linux/mac was generating so many tickets. The answer will likely help the overall product.
Personally, you need to jump through so many hoops to release software that none of these thus far mentioned should be big enough to stop you. The real reasons should be: is there a demand in this target market; will that demand generate sufficient profit?
As I'm starting my own journey on this I see all the platforms and app stores have various issues. Everything has tradeoffs. The article's author needs to come up with better arguments. I just don't see his reasons as relevant in comparison to the other much larger costs associated with development.
I'd actually recommend targeting multiple platforms just to force bugs to come out. Different platforms / compilers see and expose different issues in your codebase. So far I'm quite happy to have cross platform support even when i don't necessarily release on those platforms yet.
I find art, sound and game assets are more expensive than an apple dev account or even a mac computer. Others have written in more detail on this. Even generic business costs exceed the subscription/computer costs he's stating as being barriers.