There's some incorrect logic in there to point out.
"The math to explain this is simple: most Free users won’t give me anywhere near $3.50 worth of ad impressions."
So, a free user is less valuable than a paid user, fair enough. But not 100% of people who would use the free version will buy the paid version.
As he said in the second paragraph, "it’s hard to say which portion of the increase, if any, is attributable to Free’s absence"
While I'm not saying this is for sure, it is a possibility that, while one user with adverts gives him less money than one user who pays, cutting off all the free users could lose more money in advertising than it generates in sales.
Agreed. Since his logic of "no one seemed to care when I removed the free version" implies that very few people who download the free app would ever buy the paid one, it seems strange that he would compare the sales directly. If the free version is only downloaded 3x as many times as the paid one, then each free user only needs to make $3.50/3 in ad revenue.
But as he points out there are other costs to be taken into account. The amount of ad revenue can't be directly weighed against the money generated by sales. You also need to consider the development costs of maintaining the lite version, deciding what should be a universal feature, etc.
Sure, I'm not arguing for/against removing the free version, just with the logic of comparing the advertising revenue per person with the cost of the paid version.
"The math to explain this is simple: most Free users won’t give me anywhere near $3.50 worth of ad impressions."
So, a free user is less valuable than a paid user, fair enough. But not 100% of people who would use the free version will buy the paid version.
As he said in the second paragraph, "it’s hard to say which portion of the increase, if any, is attributable to Free’s absence"
While I'm not saying this is for sure, it is a possibility that, while one user with adverts gives him less money than one user who pays, cutting off all the free users could lose more money in advertising than it generates in sales.