I think that ELD is trying to say that, because probability is conserved, the remaining door has probability 2/3 being the right one ( 1 = 1/3 + 2/3 ).
BTW odds is not the same as probability. Probability is the ratio of the cardinality of a subset of possible outcomes, to the cardinality of the set of all possible outcomes. Odds is the ratio of the cardinality of a subset, to the cardinality of the complement of that subset.
In this example, the probabilty of the initial door being right is 1/3. The odds is 1/2. The probabilty of the remaining door, after the reveal, being right is 2/3. The odds is 2/1.
