Replace dish with drink (or worse, joint). Do you still think people who "decline to try" have a problem? That they should try in case they might like it?
I'm really NOT keen on trying chocolate-cover ants, thank you.
Some people are vegetarians. Others are Muslim or Jewish and only eat halal/kosher foods.
Many groups are discriminated against (historically or presently), and members of those groups may not be too keen to open themselves up to unfair stereotyping. I've dated a girl who would never tell a prospective employer she was Jewish; she just wouldn't eat a pork dish and would probably seem evasive to you.
That doesn't even account for those who may just be squeamish or petrified of insects. Still others have embarrassing dietary restrictions.
It's hard to fathom when you have mainstream traits and limitations (it certainly was for me), but many people who consider themselves others are reluctant to give away information that could later be used to hurt them. Sadly, this reluctance is often justified.
Food is so so so personal and cultural. It's insane to believe someone not eating/not eating a particular food has anything to do with workplace performance.
As metaphors go it's actually pretty good: people often have very specific, very individual, and entirely valid reasons to not eat something. Just as they can have the same for experiences under different conditions. Change the conditions, and you might get entirely different outcomes.
What I'm saying is, the one-shot impressions from interviews are horribly inaccurate. There is simply not enough data, plus the measuring instrument (interviewer) is flawed also in nonreproducible ways.
A simple thought experiment: let's say I build a machine that measures confidence and ability to read the room. Would it select different candidates than you?
I'm really NOT keen on trying chocolate-cover ants, thank you.