I’ve wondered this myself and came to the conclusion that it just can’t happen. Worst case is that grabbing the trim wheel will (in theory!) block any stabiliser movement. The architecture was investigated in detail following a near fatal accident on a training flight and you’ll find it in the official report.
The 787 also has a set of stabiliser cutout switches and associated procedure. Whether this is actually necessary - since the trim switches don’t move the thing anyway except in direct mode - or just to maintain fleet commonality is a different question.