I suppose the obvious question in regard to Tropic of Orange is: Is it science fiction?
Well, when time and space warp and change, it seems to put the ball pretty squarely in the science fiction court. I think the problem with being willing to recognize that is, simply, a lack of specific mediation within the text that makes this overt.
Let me toss out an example. In the 1951 classic When Worlds Collide, the earth is doooomed by an imminent collision with another celestial body, and only the top brains are aware of the situation. The bulk of the characters within the film and in the audience must have this information relayed to them by these specialists. However, imagine a retelling of this story where there are no capable specialists available. In the case of When Worlds Collide, simply have the collision occur in the year 951, instead, so that the plot follows court astrologers serving the Liao dynasty in northern China who are tracking some interesting portents in the sky and attempting to divine their meaning. The audience, too, is limited to what these astrologers can surmise, so, life just keeps going on until the screen goes black, because in 951, they have no way to abandon the planet, as they do in the 1951 film.
In Tropic of Orange, there is no one (no Neil deGrass Tyson) who is remotely equipped to deal with the problem of the twisting of time and space comes into contact with the phenomenon, and so the event is in no way mediated for participants or for readers.
That said, two more quick points.
Probably the most interesting thing is that the phenomenon does not need to be mediated for so many of the participants, as the perception of the anomaly is not universal. On the one hand, this may call into question whether or not the event itself is a universal one, or whether those witnessing it have some greater capabilities than those that do not. On the other hand, given the use within the text of layers of media used to separate characters from the necessity of interacting with the reality of a community of humanity, the inability to see a physics problem of that magnitude should not be surprising in those who have practiced the art of ignoring problems. Homeless reality television gets top ratings as a spectacle, but not as a means to address the social issue; Gabe is obsessed with escapist tropes, including his attachment to a fictional noir California past, and is only incidentally broken out of this time-warp by his unwilling exposure to technology. The fact that his involvement in technology results in being less connected to the world is an additional problem.
And, of course, when I say that there is no one capable, I refer to the guys in the lab coats, back in When Worlds Collide. Arcangel, it turns out, is capable of dealing with an apocalypse, in his own fashion. He is clearly a specialist, but his exposition of events that might mediate for the audience is a little too specialized to clearly enlighten.