Bad code will be unreadable in any language of course.
Yeah I'm talking about good code, or at least not bad code. Let's not "no true Scotsman" this.
Even for good code you don't need syntax highlighting to easily see which identifiers are function names and which are their parameters in Rust.
Well not nothing. Android apps are quite easy to reverse engineer so there would be a high risk of them getting caught which would be quite damaging for WhatsApp's brand.
I wouldn't say it's a lot, but it isn't nothing.
There is certainly nothing technical stopping them from doing it, but that's true of Signal too.