Ok as I understand it portable generators, at least below some wattage level (and a fairly high one way more than you will wish to lug about) do not require a safety ground and often the "Ground" wire is "n/c" (not connected) This was also true of my Onan 5500 on my class A:
Is this a problem... Normally NO
However if you have a quality surge protector, the kind that protects against HIGH voltage, LOW Voltage and other faults. Like a Progressive Industries PTX-50C (or 30c OR HW 50/30 C.. it will often complain about the "Open ground".. This is easily fixed.
WHY is this so?
The "Mains" power.. neutral is bonded to earth ground. IN fact back in WWII there were many houses wired with a SINGLE wire from the pole to the house (This was, back then 110 volt, now 120, not 120/240 like today's 3-wire systems) the Ground was used as the "neutral" return to save on wire, which was needed for the war effort.
Some homes are STILL wired that way
So if you are holding a tool.. hooked to "mains" power and there is a hot-case short YOU become the neutral return line.. OUCH... Several TV shows fictionally showed what really happens (Death was often the result.... When it happened to me well.. I react differently or rather did and I threw the hand grinder instead of clutching it) Still Ouch though..
But with the generator. IT IS NOT GROUNDED. thus that simply can not happen... You are double insulated or more (3rd wire ground not needed on double insulated stuff)