The independent guy is correct and it only takes 1 km to damage an automatic transmission with low fluid much less 50 of them.
The foreman is just trying to brush you off (standard operating procedure) and sometimes you have to push the issue. Don’t be surprised if down the road at some point the transmission starts to act up.
The foreman claims 40 years of experience. Forty years of experience at what; operating a fast lube facility?