It would certainly stand to reason, since they're apparently using a one-off run of Seasonics with a reversed fan in the newly-designed Sierras.
Unsubstantiated claims.
HF reported signing a deal with SeaSonic. The deal said nothing about a custom run.
Some people have speculated the PSU fan operates in reverse. HF hasn't stated that.
Extremely likely the PSU are the same exact SeaSonic models you can buy from newegg.