It makes it unreliable. If you’re claiming the IPC is an unreliable source, you need a reliable source to back you up on that. (And neither article actually cites any data that would undermine the IPC’s case.)
I’m genuinely open to being convinced. Another comment raised the issue of insufficient CDRs for IPC 5 status, which may or may not be relevant. But these UN Watch interviews are rally the base stuff, not argument.