They literally told you in their own bluepost that its emulated and they recreated it.
This clearly states that 1.13 uses multiple game loops instead of the original singular one. All they did was put spells on low priority. Now while this may come close to original batching it is doubtful this system handles everything exactly the same as the original client did. Its just not trustworthy, considering what 1.13 else screwed up ever since its inception.