Wait.

The IRS is millions of items behind on processing paper returns and responding to mail.

Does he have a local IRS office he can go down to and get any info about the situation?

Ive got a client with ne stuck in a similar time frame, he ended up with an ID verification, had to go down in person, couldnt get verified online or over the phone.

This is assuming you efile or file it for them, of course, because you posted in the ProSeries section. Have you used your preparer's resources to investigate?

I like the "Congressional Inquiry" route.  Unless you live in the District of Columbia, you have three elected officials on Capitol Hill representing you.  Send one of them down the street to knock on the IRS's door.