What Senechaud is proposing is that not far off from the Hayes Code.

I don't think it's so much that games depicting war crimes shouldn't be allowed to exist, but rather wanting a game (or more games) to depict realistic consequences.

His stance is also based on the premise that video games now have realistic enough graphics that they could be used to fake footage of real war zones.

That's not true at all. It's not about faking footage, it's about the games being realistic enough to feel immersive. From their website:

The ICRC is concerned that certain game scenarios could lead to a trivialization of serious violations of the law of armed conflict. The fear is that eventually such illegal acts will be perceived as acceptable behaviour.

If their concern was about fake footage, they'd be calling for it not to be depicted at all.