f3 is definitely safe.
EX elbow is +5, so the only basic low that will get stuffed is d4. You can't jump out of d1, and a followup elbow attempt is only escapable by jumping. With 2 bars, EX elbow on block presents a guessing game (Unless you have armor, of course). Do I stay grounded and have to deal with another EX elbow, or do I jump and risk getting juggled into EX forceball back into a reset? The only problem is obviously Reptile is otherwise too slow to take advantage of the +5 reliably, which isn't all that bad, tbh.
Now, the reset, elbow cannot be jumped out of, and d1/d3 will not land because Reptile is too far away for them to connect, so they can be jumped.
It all makes sense, don't worry.