I'm about as far from being a mechanic as you can get, but I agree with the statement that you shouldn't leave the oil in longer with synthetic. My reasoning (which may not be correct) is that without a filter, contaminants in the oil are more likely to cause trouble.
I would agree with this statement to an extend
a) depending on how often to change your oil, 500, 1K, 1.5K, etc.
b) On the conditions you ride in, rainy weather, gravel roads, high construction areas, dust, etc.
c) how hard you ride, drive like a wimp never see over 25mph or do you run wide open all the time?
d) weight, hills, temperature
All these factors play into how often you should change oil.
Synthetics do have a higher tolerence to break down over conventional non synthetic oils.
Oops also with fuels that have ethanol added to them I believe this tends to wash past the rings and contaminate oil a little more then fuels that dont have ethanol.
So, really there is no correct answer on how often you should change your oil.
Go by smell, and color of the oil and your budget!
Changing oil is like taking a shower, you can never do it to often but there comes a time that you can be OCD