What does "deterministic" mean in the context of memory management?
So what does "reference counting is deterministic" mean, if anything?


It means it is deterministic in the absence of multiple threads. Threads almost always ruin this sort of determinism, with or without a race condition, memory collection or whatnot: in one run, thread A, can be scheduled first a bit, then another thread, B gets scheduled a bit; in a second run, the OS can schedule the threads to run in the opposite order, thus almost all threaded programs  inherently lose this determinism. 

Therefore "race condition" and "threads" usually put a procedure out of the scope of this use of this meaning of determinism.