Before going into the specifics of this setup I need to point out the following: the gyroscopic effect occurs in response to motion.
Of course: that looks like useless nitpicking; if there is an unopposed torque then motion will occur anyway.
The reason for emphasizing this distinction: it is not the case that a gyro wheel starts precessing motion instead of yielding to the torque. In order for the precessing motion to start going the gyro wheel must yield a little to the exerted torque.
This must-yield-a-little was experimentally confirmed with a table-top experiment, by Svilen Kostov and Daniel Hammer (2010). Article available on Arxiv "It has to go down a little, in order to go around"
The mechanics of the gyroscopic effect is described in a 2012 answer by me: Gyroscopic effect
For the following I will assume that you have absorbed the description in that 2012 answer.
I will assume a specific friction is available to provide quick damping of any nutation. (In classroom demonstrations it is customary to suppress nutation. Most demonstrators are unaware that they are actually applying an intervention; suppression of nutation. Nutation is an essential aspect the dynamics.)
For the setup in the images you provided:
Without the obstacles the wheel would, after yielding to the torqe a little, start moving in precessing motion. That precessing motion gives rise to a tendency to rotate in the direction opposite to the exerted torque. That opposition acts against the tendency of the exerted torque.
For the setup in the images: the obstacles prevent onset of precessing motion. Without that precessing motion there is no opposition to the exerted torque. As a consequence the wheel will just keep yielding to that torque.
The motion of yielding to the torque causes the axle to push against the obstacles. Since this is an idealized thought demonstration we assume that that contact is frictionless. If the contact is frictionless then the push against the obstacles is without effect