If he said he would pay for damages when he borrowed the car then I think he should do what he said he would do.
No matter how qualified a guest driver is...
he is getting into an unfamiliar car that in many cases may have preexisting issues.
That is why I imagine a lot of Journalists don't drive every car they feature.
I no longer drive other people's cars or lend my car to a anyone.
I agree though if you just give your keys to somebody you can't expect them to pay for any damage.
But there are examples of good writers that may have used bad judgment in borrowed cars.
A journalist was writing an article about a local 911.
The car owner had offered that the Journalist could lap it at our local AX.
On his second AX lap the journalist had a wild spin with no damage.
When I saw him in the pits I asked him...
Do you know the first thing I think about when I spin on this track?
Light poles.
There was a journalist decades ago that got to test drive a top shelf 935. He wrote about the drive and how at the completion of his lap session he whistled into the pit entrance at 80 mph. He clicked off the motor and coasted the remaining couple hundred yards, maybe just to save time on the engine. As he coasted to a stop the mechanics were livid as the engine/oil pressure was off but the twin turbos were still spinning with no oil pressure.
When the Porsche GT first came out a few invited journalists smoked a clutch or worse.
I'd rather give my keys to a car journalist than an actor any day.