The starter clutch shouldn't be disturbed if you didn't remove the alternator. All the assorted parts are held in place unless you pull the rotor... and generally shoot out around the shop when you do.
This is a one-way "sprag" clutch, letting the crank rotate forward freely but allowing the starter gear to drive it forward. When the engine is running, centrifugal action forces the 3 rollers out and there's no contact or wear.
So... if the clutch is OK (they do fail: the rollers can crack, caps can wear through and entangle the springs, springs can break, and the housing (#3) can itself crack apart) then nothing you do to the starter can freeze the engine. A seized starter motor would make it impossible to manually turn the engine backwards, but turning or kickstarting "forward" there would be no effect at all.
Even a seized starter clutch will only lock he starter motor to the crank, it is not really hard to turn the crank backwards and force the starter to turn... we often do so when setting ignition timing.
So, in conclusion... if the engine is locked solid I don't think the problem is your starter motor.