Admittedly, that's a good find.
If I were you, I would ask myself: How do I know that this is the only person in this location, at this particular time?
It helps if the person has a fairly uncommon name, first and/or last name. David Bell (or Bells) doesn't look uncommon to me at first glance.
One of the clinchers in finding Census records is family relationships. The more family members, names and ages, that line up, then the higher confidence that I've found the match. I see in this profile there are no other family members in relationship. So it makes it challenging to say that the 1940 Census record you found is the exact match. Are there other sources for names of family?
The location find is some good digging though.
I wish I had a better answer for you. This is just my 2 cents.