This is not supported by either Rolls Royce (The Jet Engine) or General Electric (The Aircraft Gas Turbine Engine and its operation), each of whom stress the reversal of gas or cold stream flow as being the means by which speed is reduced with no mention of the effects of inlet drag.
I'm not sure that either RR or GE dispute the effects of inlet drag. After all the design, and operating characteristics of the reverser falls under the domain of the aircraft designer.