I also would call him back and say you aren't accepting any new clients at this time.  I did that a number of times this year.  I hate if someone leaves me hanging so I would never do that to anybody else.  A polite thanks, but no thanks, is much more appreciated than ignoring somebody.  You never can tell when you might cross paths again and it is better to be remembered for being polite than being remembered as "you were the jerk that never got back to me."