You'll need to learn it eventually sense Maya and Max are the two most popular modeling apps in the industry, so why not do it on your own time and at your own pace instead of waiting to be forced to learn it? If you can get used to Maxs modifier stack replacing Mayas History, and a lack of marking menus, you'll be fine.
Definately worth learning Max if you get the internship, it'll look good you wanting to learn their workflow. Studios usually modify Maya or Max to suit their pipeline so you'll always be learning some new program anyway. I was like you, a Maya user learning Max, and knowing Maya will mean you should get to grips with Max…