I'l give you Chrom, but regarding the question "why would anyone leak Ken?", it's simple: Vergeben Piggybacking. When Simon was mentioned, he bacame a staple of Smash Ultimate fake leaks because Vergeben mentioend him.
The first time Vergeben mentioned Ken was
way back in August 18th, literally a month a go, so it's been a while since he mentioned this. If this image came like, a day or week after Vergeben mentioned Ken, i could see your point (because i dobut you could fabricate this in just a few days), but it's been a month and as such i wouldn't be surprised that if this hoax started beign fabricated as soon as Vergeben said the word "Ken" in GameFaqs.
Let's assume for a second this image is fake. Why would he choose Ken? Because he choose a character that was expected or desired (or at the very least heavily disscussed) in order to make the leak more believable and/or interesing to the community, because it would play into their bias ("this leak includes a character that is highly expected, disscussed and desried among the community, therefore it has a chance of beign real!") and people would talk about it.
For instance: A "leaked" image of say, Banjo would hold more people's interest than an image of a playable Tetris Block. Also you have to admit that doing a mock up of Ken is easier since he is very similar in looks for Ryu except for his colors and facial features. The fact that Third Party echoes are a thing, that
If this image had Simon Belmont (after Vergeben mentioned him and before his reveal) and you asked "Why would anyone fake a leak of SIMON?", we would be in the same situation, because it would be an image of a character previously mentioned by Vergeben.