You are most welcome! I should thank you, Skydive, for broaching an interesting topic like this.
I think this QG conjecture is a longshot, as any proposed explanation for FRBs would be at this point. It's worth reviewing how Barrau, Rovelli, Vidotto addressed these issues a year ago, in their September 2014 paper. They already discussed some unresolved tensions in that paper and suggested possible solutions. It will be interesting to see a followup paper, hopefully before long.
In the meantime I'll point to some sections of the September 2014 paper:
http://arxiv.org/abs/1409.4031
Fast Radio Bursts and White Hole Signals
Aurélien Barrau,
Carlo Rovelli,
Francesca Vidotto
(Submitted on 14 Sep 2014)
We estimate the size of a primordial black hole exploding today via a white hole transition, and the power in the resulting explosion, using a simple model. We point out that Fast Radio Bursts, strong signals with millisecond duration, probably extragalactic and having unknown source, have wavelength not far from the expected size of the exploding hole. We also discuss the possible higher energy components of the signal.
5 pages, published in
Physical Review D (December 2014)
http://inspirehep.net/record/1316456?ln=en
==quote from page 2==
These signals are believed to be of extragalactic origin, mostly because the observed delay of the signal arrival time with frequency agrees quite well with the dispersion due to a ionized medium, expected from a distant source. The total energy emitted in the radio by a source is estimated to be of the order 10
38 erg. The progenitors and physical nature of the Fast Radio Bursts are currently unknown [42].
There are three orders of magnitude between the predicted signal (5) and the observed signal (7). But the black-to-white hole transition model is still very rough. It disregards rotation, dissipative phenomena, anisotropies, and other phenomena, and these could account for the discrepancy.
In particular, astrophysical black holes rotate: one may expect the centrifugal force to lower the attraction and bring the lifetime of the hole down. In turn, this should allow larger black holes to be exploding today, and signals of larger wavelength. Furthermore, we have not taken the astrophysics of the explosion into account. (The total energy (3) available in the black hole according to the theory is largely sufficient --–9 orders of magnitude larger–-- than the total energy emitted in the radio estimated by the astronomers.)
==endquote==
The next paper (though not explicitly about FRBs) could indicate the direction that Planck star research is going---detailed modeling may significantly modify expectations about astrophysical Planck star lifetimes.
This could have an impact on the FRB question:
http://arxiv.org/abs/1412.6015
On the Effective Metric of a Planck Star
Tommaso De Lorenzo,
Costantino Pacilio,
Carlo Rovelli,
Simone Speziale
(Submitted on 18 Dec 2014, last revised 9 Mar 2015)
Spacetime metrics describing `non-singular' black holes are commonly studied in the literature as effective modification to the Schwarzschild solution that mimic quantum gravity effects removing the central singularity. Here we point out that to be physically plausible, such metrics should also incorporate the 1-loop quantum corrections to the Newton potential and a non-trivial time delay between an observer at infinity and an observer in the regular center. We present a modification of the well-known Hayward metric that features these two properties. We discuss bounds on the maximal time delay imposed by conditions on the curvature, and the consequences for the weak energy condition, in general violated by the large transversal pressures introduced by the time delay.
10 pages, many figures. Published in
General Relativity and Gravitation (March 2015)
http://inspirehep.net/record/1334933?ln=en