Motor current consumption and power do not match
It's right there on page 1 of the data sheet. The graph below shows the power output curve being 1.5 watts: -



What you have calculated is the electrical input power and this does not equal the mechanical output power (\$2\pi n T\$).

Take the example at 10,000 rpm. That's 167 revs per second (n above). Multiply it by torque (approximately 1.4 mNm) and you get 0.2333. Multiply by pi and 2 and you get a wattage of 1.47 watts. That's the output power.