The only thing to take away from the pi fast benchmark, is how quick a cpu is at running pi fast. Literally, that is it. I don't see any correlation from running pi fast, to running any other particular game or software. If I want to know how well a cpu performs running something, I'll search out specific benchmarks similar to the conditions I'll be running with (cpu / gpu and other hardware).
Is pi fast a good indicator of single threaded cpu performance? As a legacy test, perhaps. I have no idea what extensions it uses, so it may well be biased towards one particular set of cpus, which looking at this thread it most definitely is. I wouldn't think my 7 year old Intel i7-2600k is better than the AMD R7 1800X, not even remotely.