I agree.
Probably, but honestly the hole not in use is going to collect sand and dirt anyway, and the grease will likely no longer exist in the unused hole after a few rides.
Probably better it exists for initial installation than not.
A qtip and some wd40 would fix it quick if the grease bothered you. I’m guessing they ship them that way so that it’s greased regardless of which hole gets used.
I’ve seen the topic of blanking plugs discussed on here a few times I think. I’m sure if you peruse eBay you’ll find some suitable blanking plugs or grommets, (the sort of ones used for blanking the holes in hydraulic cylinders etc to keep dirt out before fitting) come to mind.
Alternatively you could put a bit of duct tape one either side… doesn’t quite have that aesthetic appeal though 