hans brinker
The thrust lever won't close by itself ordinarily, although there is one particular case where that certainly will occur. A clutch problem will leave the thrust lever at a position, anywhere along the available TLA's.
The problem with an asymmetry while on APLT and without rudder input is not a VMCA issue, it is simply that there is an APLT roll input to maintain attitude due to uncorrected yaw, and the APLT will happily apply the roll input until it doesn't. If the APLT roll authority is limited, then eventually a roll-off that exceeds the APLT limits can occur and the APLT disconnects. at that time, the Roll input is removed, the yaw remains and a rapid roll occurs. The authority to stop the roll is lower than normal due to the roll induced by the yaw, so recovery is less than expected in normal handling, and on occasions that has resulted in confusion in the cockpit. (I observed that in a B744 on one occasion, and the roll in the screw up was sufficient o leave a well-deserved scar on the loopy captain's RH forehead from the storm light switch poetically shaped as a blade).
Within the normal envelope of the APLT, if the APLT is disconnected the crew may not be ready for the removal of the force of the APLT on the ailerons, which will rapidly return to neutral unless counted by the driver. That may seem obvious, especially when the driver is going to be trying to pickle off the APLT from a control position that is decidedly not neutral, but often crew will not be ready for the loads that are being assumed by them to maintain the current control position. An insidious problem can be encountered as well if the driver happens to mistakenly use aileron trim instead of rudder trim while the APLT is engaged. On too many aircraft, doing that will not disconnect the APLT immediately where using the stab trim will, but the extent of trim input is not observable on say, Boeings... and so a wild ride can occur at disconnect if it is not recognized.
All of these issues should be nonissues, but then that is the case with most accidents and most human endeavours; when the humans understanding of their state differs from actual, wild rides happen. If you are not used to wild rides (and even when you are) they can escalate rapidly as the human scurries to get back into the loop, which means doing all of the OODA stuff in quick time. The normal envelope of +/- 35, +25/-10 (or whatever the limits of your ride are set at) leaves a lot of attitudes and accelerations that the driver doesn't get to spend time experiencing.