When you´re going to throw the can anyway the rust wont be a problem. Black tea or coffee will cover most if not all of the plastic taste. So go for it.
But I´d still not put the esbit into the can (maybe I´m a bit too canny here <img src="images/graemlins/wink.gif" alt="" />) . As you´re going to wrap something around the can, it might be a better idea to put the bag outside too .