This corner grounded system or as you call it dead man's system Is an older style system. I am not sure why they used to engineer systems that way. The phase to phase voltages are the same so in that sense it won't short out motor windings, however phase y I ground voltages can be higher so if the motor isn't rating for the extra voltage it may lead to a ground fault. Check equipment manufacturers ratings.
As for safety, people working on this system might benefit from being advised before working on it that it is a corner grounded. Qualified electricians practicing safe work habits should have no problem identifying and safely working on this system. Whenever work is performed energized at least two journeyman must perform the work per Osha regulations