Yes, it was pure a political thing. It took many months for them to come to that conclusion if I remember well. The general public thought the same as you. He did visit after many times, certainly when they had their children. But it was made political specifically for that day to make a stance.
Scandal in the Netherlands
The news of the crown prince Willem-Alexander's relationship and eventual marriage plans to Máxima Zorreguieta caused controversy in the Netherlands. Máxima's father had been the Minister of Agriculture during the regime of former Argentine President Videla, a military dictator who ruled Argentina from 1976 to 1981 and who was responsible for many atrocities against civilians (An estimated 10,000–30,000 people were kidnapped and murdered during this and subsequent military regimes before democracy was restored to Argentina in 1983). However Jorge Zorreguieta had resigned one year before the end of the Videla regime and claimed that, as a civilian, he was unaware of the Dirty War while he was a cabinet minister. Professor Baud, who on request of the Dutch Parliament carried out an inquiry on the involvement of Zorreguieta, concluded that it would have been unlikely for a person in such a powerful position in the government to be unaware of the Dirty War.[4] Despite finding Zorreguieta to be at fault, the marriage between his daughter Máxima and crown prince Willem-Alexander was approved by parliament because Máxima herself had not done anything wrong; however Jorge Zorreguieta was not allowed to attend the 2002 wedding. Parliament's approval was necessary for Willem-Alexander to stay in line to the Dutch throne.
Visiting the Netherlands
Because of his past, Zorreguieta was not allowed to attend Máxima's wedding. However, he and his wife were invited to attend the christening of their granddaughters, the princesses Catharina-Amalia, Alexia and Ariane. The difference was that the marriage of the heir apparent was seen as a state matter, and a baptism is considered a private matter. During the baptism ceremonies (in The Hague and Wassenaar), opponents of the former Argentine military regime protested. Zorreguieta was not present at the investiture of his son-in-law Willem-Alexander as King of the Netherlands on 30 April 2013 in Amsterdam.