Let's been honest, almost every single TP have left Nintendo behind, even some that have rep in Smash.
-SEGA: They aren't relasing anything on their own for N platforms, and when Nintendo PAYED them for making 3 esclusive Sonic games, how it ended? With a decent game (Lost World), a mediocre one (M&S 2014, whch was going to be esclusive anyway) and one of the worst games of all time. Not only that, but they haven't helped in any way to develop Bayonetta 2 (which is a SEGA IP).
-Capcom is realising everything on every platform but Nintendo's. SFV is PS4/PC esclusive, the MegaMan HD Collection will not come out on Wii U (and only MOUNTHS after the PS4/XONE/PC relase on 3DS), and they have pubblished only 2 games for Wii I, which are ports of 3DS games. On the 3DS they are only doing Ace Attorney (since it sells only on Nintendo's) and Monster Hunter (which is here just because the 3DS is the most selling portable system. Some years ago, it was on PSP. If VITA was the nost sold, I'm sure MH wpuld be there).
So really, Konami is not different from these.
And the whole "Kojima is leaving" isn't relevant. Jiglypuff was added in Smash 64 as a joke, but it is still here. Ganondorf, Roy, Doctor Mario and Falco were added in Melee just for create a bigger roster, but theu are still here. Heck, Sonic was going to be in Melee thanks to his creator, but it was to late and he was added in Brawl, WHEN HIS CREATOR HAD LEFT THE COMPANY. It doesn't matter if the motive you were added in the firat place isn't anymore a thing, because you can return if people loves you. And looking at some fan polls, Sbake is very popular (he is even 1st in the Super Poll with more than 43.500 votes). Besides, both Konami and Kojima still wants to see Snake back.
Plus, Nintendo confirmed that TP are eligible for the Ballot, so it means they can add a TP, so why don't add a super requested character that is even the easiest to do (since he is a veteran with already establiseh moves, sound clipd, stage and is also easy to re-have the license for him, since legally it only needs a little operation for use again the Brawl one)?
Lol what? This is the most superficial argument used against Snake.
1) ERSB isn't the only rating system in the world. CERO (Japan) and PEGI (Europe) are important as ERSB. And you know what? They have rated Smash 4 exactly as Brawl.
2) You probably ahven't read trough ERSB' Brawl rating. They only state as reasons for the T rate were cartoon violence and crude homur. Nothing signals Snake in any means. It was rated higher probably due of Wario realist farts, realistic look and Master Hand's blood.
3)It doesn't matter for the rating fron where the contents are from, but what they do in the game. Indeed, we already have trophies of M rated games (like Fatal Frame) in Smash 4. Plus, MG: GB was rated E, and MGS
W was T.
4)Sakurai revealed back in Brawl days that Snake's moveset was carefully chosed for both rappresent MG and being Kif Friendly, so no guns etc.vas a resoult, Snake moveset isn't any more violent than any other characters (maybe just the D-grab, but they can change it to be more similar to MGS
W/V where he slash on the floor the guy).