I Think You Need a New Dealer?
If you oil light ever does come on your not going to get very far at all, never mind to a garage!!, at least. not without serious engine damage.
There are plenty of threads on the subject of varying levels of oil in the sight glass, but it sounds ridiculous for the dealer to say it's ok. for the oil to never show in the sight glass!!
You don't say what mileage your bike has done - ie low mileage usually means it still uses a fair bit of oil, but I think you should immediately put you bike on the centre stand and top up oil until it's over half-way up the sight glass, - do this slowly and allow to settle before adding more.
I would keep a note of the amount added as it may be useful for future discussions with your dealer??
Cheers.....................................Grizzly