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Pass transistors shorting out shouldn't happen in a well designed supply, this supply uses the LT1084 5A regulator, the LT1076 internally limits the switch current which gives the ramp voltage on the output.
A diode anti parallel over both devices mean that if the HT would be inadvertently connected to the positive terminal of the regulator the current would be eaten up by the relatively low impedance of the supply.
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In power supplies in some fixed installation in equipment, there is something that practically never happens, that is the output of the supply forced higher than its running voltage. So precautions for this event are mostly never taken, usually only overloaded down or short circuit protection is incorporated.
However, if there is a higher voltage low Z supply, elsewhere in the apparatus or in some external device connected to it (or even just a moderate size capacitor charged to a higher voltage) and it gets inadvertently connected to the regulator output, it is usually very destructive to the pass transistor, especially if an emitter follower configuration as it heavily zeners the E-B junction.
The best way to avoid this is a series (rather than a shunt diode) on the supply output and that can be included in the feedback loop so the diode's temperature coefficient and voltage drop can be compensated out.