Isn't it like bicycle riding? You never forget how to do it?

I think you just pointed out that he DOES need lessons.

Asking the Strassenverkehrsamt is definitely the first step and the quickest way to find out. Unless of course you wanna just keep busy on EF today.

You're right, thx for pointing that out.

That's nuts!
And outright dangerous. The motoric coordination needs significant practice. Unless trained to the contrary, the driver will tend to keep focusing on the right hand when it moves to the stick, taking focus off the road for a couple seconds during which the driver will tend to steer right (the left hand will want to follow the direction of the eyes).

True.

Also I think some classic cars that have the shift arranged on dashboard level next to the steering wheel require a totally different kind of thinking and coordination. Or where the clutch is not a pedal but some weird lever behind the steering wheel.

When things are calm and slow it's not a big deal, but come an unexpected situation and your hands and feet reflexively go to the wrong places.

You can convert a UK license to a Swiss one, and a person who learned in a LHD country can rent a car in a RHD country without taking a test.

The difference between auto and manual is minor in comparison to driving on the "wrong side".

I remember banging my left hand against the door several times when shifting gears and first driving a LHD car.

I tried to drive only automatic in the US and manual in the UK to separate in my brain the differences in driving.