Your dealer is somewhat correct. How they would expect you to hold the bike level though, not on the centre stand, while getting down on the floor to look into the sight glass, escapes me! Unless you always have a helper on hand, but if you do that while away from home and ask a stranger, expect some strange looks from the person.
There is nothing wrong with having the bike on the centre stand to check the oil level - period.
Like other misinformation in the manual, - eg. the break in speeds - the manual must have been written by a bunch of monkeys (no slight intended to any monkeys reading this). Always check the oil level cold, or after sitting for quite some time, as running it will only disperse the oil throughout the engine, where it will take time to drain down again. More time than the average person wants to wait. The only time you need to run the engine to check the level, is after an oil and filter change, as the filter will need to fill with its normal level of residual oil and you will likely need to top the oil up after running. Wait at least 20 - 30 minutes for a fairly complete drain down.
Oil does expand as it heats, which may make the level appear slightly higher after running, but this is negligible to the needs of setting to a correct level.
I and others here, have reported that the oil level appeared too high from the factory, as the level was not visible at all in the sight glass. Tipping the bike slightly to the left side though, with the wife doing the tipping, had the level appear not far off of vertical, so it was slightly overfilled. Again, not a problem and only would be if the level was so high that the crankshaft was hitting the oil in the sump.
On, or close to, the max level is fine. It isn't an exact millilitre measurement requirement.