You're wrong and you're correct.
There are applications that will benefit from higher alternator voltage output. The OP's application is one of those applications that benefits from tweaking this table.
Back in the day I had a turbocharged 2012 Camaro SS that needed just a bit more fuel flow from the ZL1 pump. The SS models only command 12.5V at WOT. Just increasing the voltage to 14.5V at WOT got the job done. The higher voltage definitely helped the fuel pressure stability. Eventually, I installed an aux fuel pump and turned up the boost.
I've used the same tweaks on several vehicles over the years with good results.
However, there are some applications, that just don't seem to help as much. Sometimes the alternator just can't keep up. You might command a voltage output that it can't produce. I had a 2015 ZL1 on the dyno this evening. (Tuned by another shop.) It made 13 psi boost max. It was very lean on the first pull. Around 14:1 AF ratio at 5700 rpm. The fuel pressure was dropping to 41 psi at that same rpm. The factory voltage output on it was already 14.5V. I could get it to go up to 15.25V. That had minimal affect on the fuel pressure. I made a couple pulls, and could only maintain 12.8:1 AF ratio above 6K rpm.
There are a few tuners that I've talked to that utilize the voltage output table as well. I haven't seen very much talk on the forums of it.