Nobody said to drive it thru the freeze plug side, it was offered that you can drive the idler shaft toward the front to dislodge freeze plug so you can then tap the shaft out the rear of the case.
The shaft the idler rides on may have a shoulder on it due to bearing wear, try lifting or shifting it by hand as you tap with hammer, the above suggestion to first tap out freeze plug then push/tap shaft toward rear of case, it will come out that way.