I think the person means that you should avoid becoming restrricted in your thinking about the case and not try to focus too much on the profile, which might lead to excluding the person you're looking for.
get locked in = get trapped?
Context:
"If I was ever 100% right on a case, that's just dumb luck. ... The important thing is not to get locked in and exclude people because they don't fit the profile."
I think the person means that you should avoid becoming restrricted in your thinking about the case and not try to focus too much on the profile, which might lead to excluding the person you're looking for.
Thank you