I think I can actually deflect this one by appeal to Actual Reality. (Some familiarity with quantum mechanics required.) Note that photons, by virtue of their momentum, have gravitational pull; yet in the quantum double-slit experiment, the gravitational pull of the photons is not enough to "collapse the waveform" as to which path they have taken. This seems to me to be exactly the same sort of "prohibited information" as in the fic. The best explanation I'm aware of for this is that the uncertainty in the quantities involved is high enough that, even though the photons' gravitational pull could in theory transmit information, in practice the resolution of the universe is simply not high enough for that to happen. The same thing could be at work here.

I feel like I just used a sledgehammer to kill a fly.