This article presents some very good technical work but does fail to mention a few interesting links and arguments. First of all, the very technical paper is arxiv:The Pauli objection and there is a nice G video:Criticisms to Time Quantization presentation as well.
The technical paper is difficult and the video is technical, but does explain things better. Essentially Maccone introduces a kind of hidden variable or pilot wave to define a kind of Bohmian time that exists independent of a quantum system.
These kinds of hidden variable approaches are very popular right now because they result in very complicated math and are usually impossible to test by measurement. So there are any number of different papers that seem all too familiar to multiversy, stringy, and loopy notions that then can all argue endlessly with each other. All involve complex math and theories that are not possible to test with measurement...and yet, they continue to evolve and propagate.
Maccone's observer clock is a particle on a determinate geodesic path in spacetime and the quantum jumps along that geodesic path are the quantum jumps for a quantum clock. The key notion is that this clock is independent of a quantum system and so keeps an independent quantum time that always runs in one direction.
Of course, the conundrum of a quantum clock is that there is no prefered direction and so giving a quantum clock a prefered direction makes it a classical and not a quantum clock. This approach just seems to surround a classical clock with a lot of quantum math but of course atomic clocks are already the clocks of classical science and relativity. This approach goes a long way around to end up back at the same place they started. The geodesic path of Maccone's quantum clock gives the determinate time of relativity while the uncertainty of Maccone's quantum system gives the indeterminate confusion of a quantum clock's past and future.
Maccone does appear to be on the right track in that determinate geodesics are a direct result of quantum gravity actions. However, there remains a fundamental uncertainty between the conjugates of matter and action along that determinate geodesic path. Since a collection of matter actions comprise a particle's path, it is the decoherence of those matter actions that then determines their sequence and therefore determines the direction of time.
Discrete quantum aether includes the uncertainty of past and future but it is aether decay that then points the direction of both quantum and classical times. Since the quantum and gravity clocks now both emerge from same aether decay of a collection of matter actions, there is no confusion of time.