That sounds reasonable, but I still think there is a mistake on a ATP Profile of Delpo, because Adelaide should be writen down not in "Non-Countable Tournaments" but in "Best of other countable tournaments". Otherwise it looks like he still can play one more torunament and count all the points he will gain.
Sorry I didn't really get your question, I think. Del Potro can play one more tournament without dropping any points, the Paris Masters. It is not listed yet, but it will complete his 18. The profile assumes that the player will enter all TMS events they are eligible for, and holds an empty place for them. If you look at other players that will qualify like Nadal and Djokovic, they also only have 17 listed now, but will add Paris.