He is using one of the different styles we have. One of our styles uses a different font to the default style you are using. In that style, it uses the same font everywhere. In the default style we have a different font in the message text to what we use everywhere else. That's what you're seeing; the same & character in two different fonts.
We don't control how individual characters are rendered beyond the font in use. If you don't like the fonts, you're free to change it on your own site.
But yes, that would be totally normal and acceptable.