I would expect someone at the patent office to be familiar with the basics of modern physics, including the "cosmic speed limit" imposed by the speed of light. I would not necessarily expect them to know why nothing can move faster than c, but I would expect them to know that nothing can and to reject a patent for something that moves faster than c on those grounds.

There is actually a specific rule for this sort of thing:

https://www.ipwatchdog.com/2011/10/11/the-patent-law-of-perp...

It is generally applied to perpetual motion machines.