Is it legal for the rules of a condo board require a two page addendum
to any lease owners may enter into with a tenant that specifies that
the tenant pay rent to the association rather than the owner in the
event that the owner becomes delinquent on the condo dues?
 
Would this hold up in the Washington DC?  Does DC Landlord Tenant law
supersede any lease provisions?

The tenant would not really be affected financially.  The rent is to
be paid either way.  The recipient is what differs.  I'm not a lawyer,
but I don't think the law cited is applicable.

Is that even really necessary?  If the owner is delinquent, couldn't
you just sue him?  In DC Small Claims Court, you can sue for up to
$5,000.  Suing in this type of court is informal and relatively
inexpensive.  If the judge rules in your favor, a judgment can be
placed on the owner which can restrict his real estate.  Additionally,
the judge can order that his wages be garnished, so you would be paid
monthly directly from his salary before he receives it.