Is a permit an acceptable form of ID to get on a flight?

In the absence of a valid photo ID, they are going to ask him a lot of questions to verify his identity. That's the simplest way to put it. A permit with no photo is not going to help much.

The vast majority of travellers with no photo ID are people who have had their ID either stolen or lost while in the middle of a trip. A police report validating the stolen ID story helps. But that isn't the case here, so an expedited passport is really the safest way to go.

A DMV issued permit with photo should be good enough right?

I guess he could bring his HS ID with photo and the birth certificate, and maybe a printout of the state ID he's ordered (order one!) and explain that California is broken and he couldn't get the ID in time. It would be a hassle, but would most likely work.

The expedited passport would be the best bet, but a bit pricey, I think.

Because of budget cuts, most high schools in CA do not offer a mandated Driver's Ed class. Back in the 1970's, yes. Now it is an elective class. Some high schools may not even offer the class. CA DMV only mandates that you have a driver's Ed class if you are under the age of 18 when you apply for a permit/license. There are many private driving schools that offer not only driver's Ed classes but behind the wheel experience for a cost. Pictured ID's/licenses issued by the CA DMV are not issued on the spot. You get a temporary one (without a photo). The pictured one arrives later in the mail.

I would advise him to expedite the state ID or apply and expedite a passport card. I believe it's cheaper than a passport and will allow him to fly between North America.

I agree with the idea of applying for a passport CARD. That can be expedited and is less expensive than a passport.

The bottom line is NO ONE that has posted on this thread really <I> knows<\i> what TSA will say or do, these are just speculation. To avoid issues, which could even vary between the outbound and inbound airports, get a passport or card