It's perfectly possible that the skill may develop more easily than you think (one can always hope...). It may be that the poor kid has never been exposed to something with rhythm! Or at least not been encouraged -- or even allowed -- clap or dance or bang along with the beat.
I have known several ballet dancers in my time with perfectly horrible senses of rhythm when they began, but who developed very quickly once they got the initial feel.
The other thing to watch with rhythm sense is that, in my opinion at least, the way people naturally feel a major pulse, and the ease -- or lack of it -- varies very widely. To use myself as an example, years ago (don't laugh) I was subjected to some ballroom dance lessons -- Arthur Murray?, I seem to recall -- and was the total despair of the teacher because although I felt the major pulse easily, I had trouble feeling the subdivisions. As time has gone on -- perhaps because I really had to work at it -- I now have no trouble with any of the more common divisions (I still get hung up on 7/8, though...) and even things like 3 against 2 -- seem natural (I still have to think about things like 11 against 3 -- think Chopin -- but I can get them).