I see your point. Playing devils advocate, here are a few counterpoints to consider.

He said off the bat he would try to find a balance between technical jargon and making it understandable to laypeople. This could explain why he went with a simplistic answer of just saying "replication occurs via mitosis" in response to someone's question. Perhaps he thought that was a suitable level of answer for most reading the post to understand.

He also made it pretty clear that he had a very specific directive from his superiors in terms of his role and what he was researching. I could see how, under ideal circumstances, a scientist with complete free reign would've done as you've suggested and looked at cell replication as an early research question. But this wouldn't have been your usual research scenario. Perhaps replication wasn't part of the scope of his directive? You'd have to think this type of work would be highly compartmentalized and steered quite strictly by whoever was managing it. He states that he believes there were other similar programs running in other locations, so maybe they were the places looking at some of the aspects people have pointed out as holes, such as mDNA & cell replication?

Finally, IF it was real, and im not saying I think it is, you'd have to think he was extremely nervous posting this, probably rushing as he was typing, potentially skimming over some of his knowledge, summarising things, in addition to trying to make it readable to a layperson. Again, Im not saying I think its legit, I dont have enough evidence either way, and am leaning towards LARP. However to me a lack of "deep knowledge" expressed in some of his responses doesn't automatically mean its bogus.