Well, I know Nintendo wouldn't hesitate to put the actual logo for an M-rated fighter from an M-rated franchise if the presentation is dedicated to them. I can understand removing the logos for Assassin's Creed, Fallout, and No More Heroes, because why should a video dedicated to a E10/T character have to have an M rating just because a logo appeared for a second?I'm pretty sure the rule came out after Joker was released. The YouTube videos presenting each of the fighters ESRB at the start are.
The whole situation is dumb in general, because an M-rated Mii Costume can appear in a presentation and the video won't have an M-rating on it, but because the LOGO appeared now it would have an M-rating. Stupid.