Zero's whistled S is probably something he learned speaking Indonesian - I've heard it with native I. speakers.
I didn't notice Hirono's S, but it could be cultural too. If her family isn't long removed from Japan, I would expect an S sound made with the tongue a little looser on the upper palate than an English S.
The ssss’s with osama was kind of a Chicago thing too though, like, da bearsss. Let’s have some beersss.