If you're talking about the actual vehicle motion control systems, they probably should have been looking at what languages avionics companies use, not what their app developers are familiar with.
You'll need languages and operating systems that are battle-tested (literally) in hard-real-time fault tolerant systems.
Swift should never have been on the whiteboard for something like that. It's never been used in that scenario.
Avionics companies have very complex rules. They can use any of the above, but generally a subset.
For example you might use C, but ban malloc, and recursion. There will be static analysis tools that look through your code and calculate exactly how much memory you are using using in the worst case of function call tree, that way they know they cannot run out of memory or stack.
