I think that's obviously a matter of opinion. I don't think Rust is hard to read at all, nor do I think of it as being particularly sigil heavy, but that's me. I think the syntax is probably unfamiliar for some, and familiarity is almost always what people mean when they say "readability".
Coming from c++, Rust was pretty familiar. PHP isn't that hard to read either.
Most Rust programmers just never, ever have to deal with pointers like this. And most code in the wild looks nothing like this. Yes, it's there if you need it, but in practice you will never read anything like it.
Readability is the most suspect of all the anti-Rust arguments to me, because, as others have noted, it's almost always about familiarity. The most senior parent comment is someone explaining how their 100KLOC PHP command line program(!) was more concise and readable than Rust! PHP as the exemplar of readability. Think about that.
Look -- if I really loved PHP and was forced to write Rust, I might really hate it. But I think the world of people who really love PHP is pretty small compared to the world of people who have lived with PHP because that was what was familiar. Folks let's climb off the bus to crazy town.
Coming from c++, Rust was pretty familiar. PHP isn't that hard to read either.