I wouldn't chance it.
To me a single function is the complete cycle, so trigger pull and trigger release. The trigger is spring loaded so it is going to return automatically, you aren't forcing it to return. 

Realistically it probably will never come up, but I won't chance it for a product I don't think that great anyway. Take the risk if you want but I think people should be aware this is in a gray area.

I wouldn't chance it.
To me a single function is the complete cycle, so trigger pull and trigger release. The trigger is spring loaded so it is going to return automatically, you aren't forcing it to return. 

Realistically it probably will never come up, but I won't chance it for a product I don't think that great anyway. Take the risk if you want but I think people should be aware this is in a gray area.

Once the ATF approves and has a letter of approval its basically set in stone. This binary trigger is 100% legal.  Unless a state or the fed bans it specifically.

Ok, who's brave enough to try one of these puppies with a slide fire stock?

Fortunately you are not the ATF or authority on this matter

The trigger has a serial number. . . why? 

I quoted Hawaii law, not federal law. I specifically said that there could be an issue with Hawaii law so quoting the ATF doesn't solve the issue I raise.

I quoted Hawaii law, not federal law. I specifically said that there could be an issue with Hawaii law so quoting the ATF doesn't solve the issue I raise.

Both Laws are written exactly the same


26 USC 5845(b)
Machinegun
The term “machinegun” means any weapon which shoots, is designed to shoot, or can be readily restored to shoot, automatically more than one shot, without manual reloading, by a single function of the trigger.

HRS 134-1
Automatic firearm
"Automatic firearms" means any firearm that shoots, is designed to shoot, or can be readily modified to shoot automatically more than one shot, without a manual reloading, by a single function of the trigger.

I quoted Hawaii law, not federal law. I specifically said that there could be an issue with Hawaii law so quoting the ATF doesn't solve the issue I raise.

Both Laws are written exactly the same


26 USC 5845(b)
Machinegun
The term “machinegun” means any weapon which shoots, is designed to shoot, or can be readily restored to shoot, automatically more than one shot, without manual reloading, by a single function of the trigger.

HRS 134-1
Automatic firearm
"Automatic firearms" means any firearm that shoots, is designed to shoot, or can be readily modified to shoot automatically more than one shot, without a manual reloading, by a single function of the trigger.

Both Laws are written exactly the same


26 USC 5845(b)
Machinegun
The term “machinegun” means any weapon which shoots, is designed to shoot, or can be readily restored to shoot, automatically more than one shot, without manual reloading, by a single function of the trigger.

HRS 134-1
Automatic firearm
"Automatic firearms" means any firearm that shoots, is designed to shoot, or can be readily modified to shoot automatically more than one shot, without a manual reloading, by a single function of the trigger.

Ok, fair enough.

But my follow up question is this: Do you trust local prosecutors to interpret the law in line with the way the feds do?

Our 2nd amendment in Hawaii is worded the same as the US constitution with one small word difference yet federal gun rights and Hawaii gun rights are very different.

Like I said, I don't think it will ever come up, but just want to throw that out there for consideration.

Ok, fair enough.

Federal ruling > Hawaii ruling.  If the fed makes a rule and the state makes a rule against that rule.  The federal rule wins out always without question.