Why would somebody put a grease cup where the acorn nut goes on the carb bowl cover? They lost the nut, or some other reason? Also why do some LFs have a part that sticks out under where it bolts to the intake? Mine doesn't have that. I drilled a hole in a lawnmower air filter once and put a grease cup so I could pour gas in to prime it every time, but there is already gas in the float bowl.
If you are talking about the banjo fitting at the fuel inlet, looks normal. Some models have them some don't. RE the grease cup, I think your guess is about right, just using it to cover the hole.
Possibly to allow filling the bowl with gas without removing the bowl cover.
I think this is the part you are asking about;