This book is, I imagine, pretty heavily biased to some side or the other, considering the author and when it was written.
Here's the relevant passage:
"The existence of feudal relations in Russia, denied by former historians, may be considered unconditionally established by later investigations. Furthermore, the fundamental elements of Russian feudalism were the same as in the West."
It seems like he's implying Russia had been treated unfairly by the West. But he isn't kind either. Also says that the lack of evidence "testifies to the incompleteness of Russian feudalism, its formlessness, its poverty of cultural monuments."
Is any of that true, or related to the first question?
There was a disagreement about feudalism in Russia. The argument that Russia was a feudal society is written by Nikola Pavolivich Pavlov-Silvanskii in a 1907 book called Feodalizm v drevnei Rusi (Feudalism in Ancient Rus). editheres the three traits pavlov says define feudalism- division of the country into independent and semi independent land holdings, seigniories; inclusion of these land holdings into a single system by means of a hierarchy of vassal relationships; and the conditional quality of the possession of a fief. edit
The book i have says his view has become mandatory for communist historians but that it isn't shared by uncensored historians.
{Trotsky probably brings it up because of the marxist theory of history having a societies progress in certain ways and "feudalism" is a stage but im not familiar with all the ins and outs and definitions about that}
It comes down to how you define feudalism and if you want to point out similarities or differences.
There was no vassalage in the western sense in Russia. Boyars served princes but there was no mutual responsibility. There is no subinfeudation, Some boyars had their own retainers but there was no ties of fealty from prince to boyar to retainer.
In Europe fiefs given conditionally for service was a dominant form of land tenure. There was no conditional land title in Russia until the conquest of Novgorod in the 1470s. Russian land was votchina goods and power inherited from your father, alodial title.
The back and forth of responsibility, reward is a contractual relationship in western europe so it can be nullified by violation by either party. Laws and courts are needed to adjudicate disputes regarding those contracts.
The boyar to prince relation has no contractual back and forth so no real laws or courts are needed. If the boyar is dissatisfied his recourse is to leave.