I'm betting that the whistleblower went directly to Schitt and there was one witness to the meet. There is likely a call or email preceding the meet OR the Schitt and the Whistle Blower met outside someplace first. Shades of Deep Throat.
Put Schitt under oath.
The Dems tried to clobber Nunes. They lost but it tied up Nunes for about 9 months.