A spinning generator is not outputting 10x it's rated current over any significant amount of time. You can only add so much steam or fuel to a turbine, and the rotor has a lot of inertia, but not enough to account for 10X its rated capacity for a second. The electrical switchyards would trip nearly instantaneously if it's connected plant output 10X its rated input.
Although I’m hardly an expert on power lines(my factory produces HV switchgear), a 1s short circuit current rating of 10x(actually more) is normal, standard to IEC norms.
A properly running grid with spinning generators never needs the 10x rated current. More importantly, oscillations are dampened by the rotating masses.
