Faeelin,
Tenner's text is erudite but I wonder why he doesn't address different financial sectors that would be huge in capitalist Russia, namely mining, energy (oil, coal, natural gas etc.) and forestry and wood industry. In short, Russia had the best resources for growth exactly in the areas he's forgetting in this piece. And these are resources were well-suited to form a basis for building a strong heavy industry in many other things than mere "railway building", like Soviet industrialisation goes to show. If even a part of the industrial potential of Russia IOTL used for manufacturing weapons for domestic use would be export-oriented (cars, aircraft, farming and industrial machinery, ships, etc.) that would be great for growth.
Also, why not contrast potential Russian growth rates with those areas that were parts of the Russian Empire that went capitalist etc., Finland, the Baltics and Poland for 1918-1940 and Finland since WWII? These nations did considerably better than what is predicted in the text for Russia in terms of GDP growth. Comparing Russia with Finland has many problems, sure, but even if Finland was among the most developed parts of the Empire in 1913, it was still a poor, highly agrarian formerly Russian area that industrialised and reached a Western European level by the 1990s. Let us add that Finnish conditions (being sparsely populated, forested, logistically difficult) are somewhat similar to Russia, with the distinction that Finland has considerably less minerals, metals, coal and oil.