I will preface this with the fact that the author worked on at least one such FPS game (Titanfall 2) and probably know what he is talking about.

He offered one solution to fix one behavior of TCP, the behavior being that if the data written to the buffer is not big enough, TCP might hold it. Setting TCP_NODELAY forces the protocol to avoid holding data. But this is only written as a note to coders who might think TCP_NODELAY will fix TCP for action games, but it doesn't actually, because the protocol has other characteristics that are undesirable in that type of games.

Moreover, you write this: waiting on a dropped packet and the delay it causes is unnoticeable. Unless you have a FPS game with TCP as its network protocol to validate this claim, I call bull. Many network programmers recommend against TCP. This is probably not simple cargo-culting.