Questioning the person who made the claim, sure. Get them to elaborate. That improves the discussion. But halting discussion until they can come up with the words of someone else to justify their claim, as seen here, just makes you look stupid. If you would rather talk to someone else, go talk to someone else instead. At the end of the day, all is fair in discussion, so go for it – call for someone else to enter the discussion if you want. But as all is fair, we're also going to call out your stupidity when you do.
Questioning the person who made the claim, sure. Get them to elaborate. That improves the discussion. But halting discussion until they can come up with the words of someone else to justify their claim, as seen here, just makes you look stupid. If you would rather talk to someone else, go talk to someone else instead. At the end of the day, all is fair in discussion, so go for it – call for someone else to enter the discussion if you want. But as all is fair, we're also going to call out your stupidity when you do.