Nicolas Sarkozy was right to call Francois Hollande 'ridiculous'. Even though a former President should not insult the current President, I think what was said was right. Ever since taking office, Francois Hollande has made some pretty stupid decisions that affect everyone in their country. The approval rate dropped and will continue to do so.
While it usually not considered proper for a previous French president to call the current one 'ridiculous', in this case it cannot be said that Sarkozy is wrong. Hollande has been absolutely ridiculous in office, advocating ridiculous and unpopular policies such as intervention in Syria and the Central African Republic. With an approval rating in the teens, it is clear a great deal of French find Hollande ridiculous, not just Sarkozy. Considering this, I think Sarkozy was justified in his description.
People have their reasons for saying things, and its great to hear a politician actually saying what they think on an issue, rather than what people want to hear, or the incredibly cleaned version passed through 100 speech makers and other politicians. Sarkozy has polar opposite political theories, and France isn't doing great economically.
Yes, Nicolas Sarkozy was right to call Francois Hollande ridiculous, because it is fair to call public officials out on their actions, public and private. Hollande's time in office has not been without scandals. It is appropriate that other politicians point out when he needs to be held accountable for his actions.
No, I don't think that Nicolas Sarkozy was right to call Francois Hollande ridiculous. It was clearly an insult based on personal information about Hollande's life, and not to mention the fact that he serves a political party with an ideology far different from Sarkozy. But since Hollande is president now and Sarkozy is not, it really doesn't matter.