That was my first instinct too, but nothing the author said indicates they actually need non-strict aliasing. If the function had been:

   void DoSomething(void* src, void* dst, size_t numBytes);

(Going deeper, non-strict aliasing applies to any pointers of the same type passed to a function. So if src and dst were both cast to float* inside the function, and if they really are both of that type (technically "an object of type float exists at the pointed-to location) then they can still alias. The char* exception is the only case that you can access a memory location through two different types of pointer and they can still alias.)

It's interesting the author mentions uint8_t. It's certainly more explicit than char, but it doesn't have the same aliasing guarantee (very strictly speaking - in practice it's almost always an alias for unsigned char or char, which does).

This is actually pretty annoying in embedded programming in C, because you'd often really prefer to use a uint8_t buffer[] for serialization functions (e.g. to write arbitrary data on some bus etc.) over char*, but you'd actually lose the aliasing permissiveness that you need (if you are strictly sticking to the standard-- this is often ignored in practice).