I think the change in flavor text has to do with its change in stats and moveset upon evo.
In Wimpod form it can't make use of its natural talent of running away when dealing with danger, it just runs in fear.
In Golisopod form it's trained/evolved to turn this weakness into a strength, as now thanks to its moveset and stats it's ability is actually extremely tactical.
Same ability yes but because Golisopod is so drastically different from Wimpod the ability becomes an entirely different beast for it.
In Wimpod form it can't make use of its natural talent of running away when dealing with danger, it just runs in fear.
In Golisopod form it's trained/evolved to turn this weakness into a strength, as now thanks to its moveset and stats it's ability is actually extremely tactical.
Same ability yes but because Golisopod is so drastically different from Wimpod the ability becomes an entirely different beast for it.