Well, For other reasons you did the right thing... but on that Honda, by default, that pin is not connectd to anything.
This is why when an RV with a Surge Guard is connected to a HONDA EU-x000i they need to make a special "Bonding plug" to bond the neutral to ground,, Ground is not connected.
The other things.... You might, some day, use that adapter in a place where the ground *IS* properly connected.
And one more thing: Why is it NOT connected on the Honda.. To fully explain this takes quite some time but basically the safety ground is there so that you do not become a "Return path" for power.. Power MAINS are grounded and thus if something goes wrong.. YOU can become a conductor of electricity.
But the HONDA is not grounded,, So if you are standing barefoot in a puddle of water on the ground... So long as you do not drop the tool into the water you should IN THEORY be safe.. I do not recommend testing the theory though, ALWAYS use safe practice.
