Tick Tock in the background noise
I hope they learn from some of the problems of the EFF's DES Cracker which was also a dedicated big of custom hardware do to one job that cost about the same when considering inflation. That machine had some defects that limited its performance and there were a few other issues that had to be solved in software after the fact.
The good thing about GPUs is you will be able to buy faster ones in 5 years that might just plug in and run the same code where the other solutions will require new hardware to see future power vs energy advantages.
One very cool feature of a Pulsar's timing is that if your atomic clock says it is drifting, you need a better clock.