Hi. I sure am having issues with WPMU plugins! Still, I'm assuming it's me.
Password Protect does not wrap shortcode around highlighted text, but merely pastes it in up top. (Highlighted material seems to UNhighlight when I click the lock icon.)
I tried wrapping the code by hand (pasting the last part of the code at the end of the material in the page. It worked, but then disappeared an hour later.