The fact is that an object of 100 kg mass, weighs 100 kg on the Earth because it is in a 1G field
W = mg ... 100 x 1 = 100
and in the lunar gravity its weight is 16.7 kg
W = mg ... 100 x 0.167 = 16.7 (disregarding mascons of course!!)
I think it's reasonable to say that a bathroom scale measures mass in kilograms
as long as one remembers how it works and the limitations of that method: by measuring the force of gravity and converting that to kilograms, implicitly assuming an acceleration of 9.8... m/s^2. I.e., it's a mass-measuring device with a mechanism of operation that works fine on earth as long as the minor variations in gravity from place to place are below your accuracy requirements, as they usually are. Any precise mass-measuring instrument of this type would have to be calibrated for local gravity to give correct results.
So I think it's simply wrong (as well as extremely confusing and error-prone) to say that an object that's 100 kg on earth becomes only 16.7 kg on the moon. It's still 100 kg on the moon, as it would be measured by a scale properly calibrated to the local gravity. It's just 6 times easier to pick up.
Suppose the bathroom-type scale had never been invented. Suppose we still measured things with the balance scale, matching the pull of gravity on our test mass with that on a set of calibrated masses. Then, without any changes, an object weighing 100 kg on earth would still weigh 100 kg on the moon, or anywhere that had a non-negligible gravity field. So would a bathroom-type scale with a built-in accelerometer to compensate for local gravity variations. I.e., the notion of the kilogram as a unit of gravity force depends not only on a specific local gravity field, but on the use of a specific type of device to measure it. That's silly.
SI carefully distinguishes between mass and force, something largely unknown to those who measure all forces and masses in pounds. It's a bit like the notion of grammatical gender in many non-English languages, only it actually makes very real sense. Just as English speakers can't impose their rules on other peoples' languages, they should not introduce their confusion between mass and force into other measurement systems.