French_Fried said:
So my band’s frontman who doesn’t play bass said that using a pick on bass is stupid

You get a totally different sound using a pick that cannot be easily replicated with fingers, so if that's the sound you want it would be stupid not to use one.
Also using a pick is often the best way to get a good quality recording. I always recommend that for players who have inconsistant velocity between different fingers. It allows you to use less compression on the input and weirdly get a more organic sound as a result.