Just to be sure clear, I'm not sure that I follow you when you say:
That being said front hubs are engaged while in 2WD.
The locking/unlocking of the front manual hubs is not influenced by the position of transfer case drive selector.
In other words, whether the T/C is in the 2H position or the 4H/L position - it has no effect on the wheel hubs. Even though the transfer case and locking hubs are the main components of the 4WD system, neither one has any control over the other.
The transfer case can best be described as the driving unit while the front wheels would be the driven unit.
The T/C output shaft (when in either of the 4WD positions), drives the front drive shaft. The torque from the front drive shaft drives the pinion in the front differential. The pinion splits the load and drives the two halves of the front axle. At the end of each axle are the hubs.
It is only when the hubs are engaged that the torque from the transfer case is allowed to reach the front wheels.
While in 4WD with the hubs set to FREE, the driveshaft and axles spin but no power is transmitted to the front tires. They appear to be driving the wheels, but are actually just along for the ride.
If the T/C is in 2WD and the hubs are locked, the front wheels (as they roll along on the road) will back feed the axles and drive shaft and cause them to rotate. But because the T/C is not mechanically connected to the driveshaft, they are just freewheeling.
Driving around all the time with the front hubs locked is not harmful to any part of the front wheel drive system.
Many people up north do this - mainly in the winter. It eliminates the hassle of climbing out and locking the hubs when road conditions warrant 4WD - and then getting out again to unlock when say they are getting on the highway.
If 4WD is temporarily required (and the hubs are always engaged) it can be utilized simply by engaging the transfer case. The only drawback is that there is a minor increase in total engine load due to the force required to drive the weight of the drive shaft and axles.