I've been using simple redirect for page redirects in a site and would like to use it for custom post types as well. Redirect meta box doesn't display in the custom post type post editor though. I went through your code and it seems like it should support custom post types as well as built-in post types, but it doesn't seem to work with custom post types.
I'm testing all kinds of options to realise why this doesn't work.
So far I suspect
$this->postTypes = get_post_types();
may return only built-in post types for some reason, could be because of lack of a specific entry in the post type itself, or
in simple redirect may have some bug in it.
I would appreciate it if you could please check this out.