My standard reply is that using a pick on a uke is like using drumsticks on bongos.
I mean, you can do it.
And there's nothing technically wrong with doing it.
And some people do do it (usually people who are coming from similar instruments where picks/drumsticks are used... i.e., guitarists and drumset players).
But, to me, it fails to take advantage of the unique and specific character of the instrument. What we think of as the "traditional" ukulele sounds is produced by using one's fingers, just as bongos are traditionally played with bare hands. The "helper tool" shouldn't be used as a crutch because you haven't figured out how to play without it. I think you miss out on a cool opportunity that way.
But if you're using the "tool" on purpose, such as for the effect of it (to get a particular sound or volume), then why not? Go for it!
JJ