I think people are trying to balance in a false dychotomy here
You could have liquid cooling, but it could be different from a car liquid cooling. For example, maybe you don't need pumps and could rely on a sturdy passive convection system. (Also include some fail-safe aspects)
The concept doesn't need to be married to modern automobile design, agreed.
Much like the transition motorcycle engine manufacturers made, moving away from air cooling in the late 70's. The first innovation being under piston oil jet cooling and then moving progressively to water cooling.
Oil cooling offers little additional risk or complication over air cooled designs, but there are limitations on liner/piston temperatures and additional vapors which increase maintenance that don't exist with water cooling.
It really comes down to whether it seems reasonable to trade on some risk for economy, but ultimately recip engine flight isn't efficient anyway
You could have liquid cooling, but it could be different from a car liquid cooling. For example, maybe you don't need pumps and could rely on a sturdy passive convection system. (Also include some fail-safe aspects)