Or, perhaps the complete opposite, where it's someone who actually knows how to benchmark JS engines because they work for deno. But we won't know unless they explain which it is.

Agreed, simply having a conflict of interest isn't a reason to disregard the complaints. But the problem is that failing to disclose it up front creates the appearance of dishonesty, which undercuts the message. But it's important for us as readers because it makes us more aware that we should be looking for some of the techniques that can be more confounding or misleading.

I want to be clear, I am not saying that the post is wrong, just that we would know to be more careful in reviewing claims.