As is the custom of the churches, the explanation is incomplete:
The root word is ya-reah from which we get the niph form of noreah which means:
1. fearful, dreadful
2. causing astonishment and awe
3. inspiring reverence
It is correct to say that Moshiach causes those observing his worship to be terrified, in dread, and astonished and afraid. Just like at Mt. Sinai. He is not a pacifist wimp but pop Judeo-Christianity inspires exactly that.
So, the fear is relative: do you fear a terrifying being more than a contemptible government.
BD p. 431