Adding more anecdotal "evidence" to the pile I guess.
The only reason I can see this working for him is if he was fighting almost purely short-range enemies. At which point HMG can work as elite PD + IPDAI provides 100% damage vs missiles. Throw in some Vulcans and you're completely covered PD and kinetic wise. However, you need the range if fighting anything that has a longer range, at which point you need to free up flux or the Dominator will flux itself out. You save 140 flux and 4 OP by switching to Flak Cannons from HMGs, which is required if you're going to run any of the small kinetics in the small front ballistic mounts. Despite being significantly lower in DPS, Flaks are also better PD as they hit more consistently and hit multiple targets.
So, it would be good against any fleet that lacks anti-shield weaponry that has a range over 940. So mainly certain Aurora builds, Falcon, Eagle, normal Eradicator built for range, and most of the capitals flat out counter his build due to having enough range and non-missile/fighter weaponry.
As long as it fights nearly 1v1 vs frigates and destroyers, it works, which is somewhat achievable as 9 Dominators can be deployed for 225 DP. Throw in 5 Brawlers for point capture can flank protection and target switching can be somewhat minimized.
It's not as good as he's trying to say it is, but it's also not terrible. Personally, I would use HMG plus front kinetics if I was using a Shield Shunt variation as dissipation largely isn't an issue. Still isn't as reliable as a couple Onslaughts with HAGs in all its large mounts, and a good volume of supporting kinetics with Ballistic Rangefinder.