Yeah he's right, an oil cooler does didly if your stopped, but were using oil coolers because most of us have modified engines which DO produce more heat even while riding. Lots of Harley riders with 100 plus cubic inch motors run oil coolers for the same reason. A stock Harley makes about 65 HP, so adding 50 HP will produce extra heat.
If your running standard bolt on's I wouldn't worry about an oil cooler. BUT once you add a higher compression piston and cam, it would be a good idea to add and oil cooler, Stock a Warrior makes about 18 HP with said mods a warrior will make close to 30 HP.