I don’t see how it’d be hard to recognize him in a hologram, it’s never been that way in a SW movie before. Just because it’s all blue-tinted doesn’t mean you can’t see the tattoos and horns.
He could be hooded. Wouldn’t hide him interely, but it might avoid confusing most viewers.
I just seems weird to me to put Maul into the film without any explanation as to how he survived. Saw Gerrera is one thing, but Mail is a well known movie character.