Unfortunately this is not possible with out default Responsive design functionality at the moment. This, indeed, is an interesting case. However, since the mobile redirect rule gets applied always, you will be redirected to the mobile version of the website every time you try to go back to the default one. What you can do is create a custom redirect rule, which will get applied depending on the value of a cookie. For example, you can store a boolean value in the cookie ("redirect"). When you the user is redirected to the mobile version of the site, the value will be true. When he clicks on the link, pointing to default website, the value of the cookie will be changed to false. Depending on whether the value is true or false the redirect rule will get applied. You might also find this articles useful:
There is, actually, a feature request on the subject. Here's the link, where you can vote for it and track its status.
the Telerik team
Do you want to have your say in the Sitefinity development roadmap? Do you want to know when a feature you requested is added or when a bug fixed? Explore the Telerik Public Issue Tracking
system and vote to affect the priority of the items