Melee attack: MAX(5, SourceCombatReach + TargetCombatReach + 4/3) + IfSourceAndTargetAreRunning(8/3)
Tauren vs Other race: 4.0 + 1.5 + 4/3 = 6.83 yards(9.49 if leeway)
Maximum leeway range of a Tauren vs an Orc:
https://i.imgur.com/AwTvagl.png
9.49 yards. Heals are 40 yards maximum, think about how far you can heal from and do a mental comparison.
As Blizzard has already told you: