[Dirkadirkastan]

You simply do not understand what home field advantage in a seven game series is.

You're defining home field advantage as "team team which, at series end, played more games at home". This has no meaningful application whatsoever and has absurd logical conclusions such as the possibility of HFA being lost while simultaneously winning games.

Here's the conventional definition: "Home field advantage is held by the team that could potentially clinch the series without any additional road wins." When a road team splits the first two games, it is said that they "steal home field advantage". This is not because the series can end in five games; that was true already. They steal home field because they can now clinch the series merely by winning out at home, whereas before the other team held that distinction.