For the B737-300/500, why does it not mention on the reverser unlocked QRH that the affected thrust lever will snap back if you this occurs or even in the FCOM of the engines section?
There is a mention of this in my old copy of the Boeing 737 Operations Manual Volume 2. Chapter Non-Normal Procedures Page 03.05.12 Date 20 December 1991.
Under the heading Reverser Unlocked (Inflight) it states (in part) "Movement of the reverser sleeves to the reverse thrust position mechanically retards the thrust lever to the idle position, and the interlock limits movement of the thrust lever as long as the engine is in reverse thrust."
This statement does not appear in later issues of the FCOM or in the QRH. I don't know therefore if that statement is still valid but certainly in the 737 Classic simulators of that era which are still used, that statement is still true. Maybe an autostow modification is the answer to your question - but that is only a guess.