Some oil in the airbox is normal. Bikes don't use a PCV valve, they just have a hose direct from the crankcase to the airbox. As your bike's oil heats up and sloshes around it vaporizes. The mist is carried into the airbox where it condenses and coats the inside of the airbox, sometimes enough to puddle a little. Don't worry about it if you can wipe it up easily with a small rag.
Now, if your rings are shot, blow-by will will pressurize the crankcase even more and it forces the oil into the airbox in large quantities. You will know the difference if it happens, it will look like somebody poured oil into the airbox instead of the crankcase where it belongs.
Rarely is the question stupid, but sometimes the answer is
you need to run everything you read online through your own personal BS meter to determine if it makes sense to you.