I agree. This is a weird reason to discontinue interviewing someone. This is the type of factoid that can easily be learned by someone on the job. If you want to reset db connections after 500ms instead of 15 seconds, then fine. But its the type of thing your company can just say they want to do and you do it, its not really something worth hiring around.
Not to mention, you really should be connecting to a DB Pooler anyway, which handles your DB connections, rather than designing the individual implementation within the application or micro-service and try to keep all your services aligned.