Try looking at it this way; FDEV could have prevented Horizons users from access to the Python Mk2 altogether and made it Odyssey exclusive, as I gather they have done with ships and DLC's in the past (before my time), but instead Horizons users can get the ship for roughly the same real world money as buying Odyssey. It's not great for us as players, but at the end of the day, they are a business, they are trying to make money.
They are trying to encourage players, without forcing anyone, into getting Odyssey; they want to consolidate the game universe. It has got to be easier and cheaper for them if everyone is running the same game. If you don't want Odyssey on principal, fair enough, but if you don't want Odyssey because it doesn't offer you anything ... well, now it does. And it's likely not the only ship they will release this way so if you plan on getting any of the new ships, it will be cheaper too. You can get Odyssey, access to the Python Mk2 and whatever other ships come along and just ignore all the onfoot gameplay.
They are trying to encourage players, without forcing anyone, into getting Odyssey; they want to consolidate the game universe. It has got to be easier and cheaper for them if everyone is running the same game. If you don't want Odyssey on principal, fair enough, but if you don't want Odyssey because it doesn't offer you anything ... well, now it does. And it's likely not the only ship they will release this way so if you plan on getting any of the new ships, it will be cheaper too. You can get Odyssey, access to the Python Mk2 and whatever other ships come along and just ignore all the onfoot gameplay.