Their argument was that he didn't know this and that and how is it that I deemed him worthy?
I interjected by saying that during these 30min I get to ask questions I don't have nearly the time to check one's skills throughly. And the same is true for them.
The most I can achieve in this timeframe is check whether the person won't be actively harmful to the project by e.g. being a charlatan or just malicious.
This was news to the delivery manager and they didn't approve of that.
I refrained from replying that our rates vs the market don't really put us in a position to be picky.
But I did tell them that I worked with "net negative" people(with examples) and it's really not about the skills at the moment of hiring.