There is already a Fedora account named rahul, although they are inactive. CCing Toshio and Mike - any thoughts on what would be best in this situation?

unfortunately unless you own them both we can't do it. The problem being it's possible for inactive users to come back. Sorry Rahul :-/

Doesn't the inactive accounts get deleted after sometime?

Nope, we never actually delete accounts, as that could break references somewhere else.