NASA also agreed with the logic of "sure, we don't know how it'll perform at low temperature, but we don't know that it won't work!" that led to the Challenger explosion. They aren't infallible and they can make extremely stupid mistakes too.
I'm an engineer, and the unit mixup you've linked isn't a failure of different unit systems, it's just shitty engineering. You should always label your units. There's several domains where even a single unit system has ambiguity without labeling -- pressure with bars, atmospheres, and kilopascals.
It was the contractor (I believe it was Lockheed?) who used pounds though NASA's documentation used metric units, cause they make actual scientific contributions.