When you come to a public forum and ask strangers how to wrangle your iPad back from your 2-year old you will likely get more posts that show a certain amount of concern for your parenting than any software solutions. My solution, as a non-parent, is similar to that of a parent. That is, parent the child and not the iPad. There is no need to do anything more than put a password on the iPad (good idea for any portable iDevice) and parent that child. Explain boundaries and respect to your child and he or she will be able to apply that to 90% of their life.
No one is implying that your toddler should be prohibited from using the iPad, the article you linked to suggests that is what is in our heads. What you need to find is an article on children being in charge of their parents and the lifelong repercussions of such behavior. Google that.
Since you have already discovered that you may not find a solution in the form of an application, perhaps you can take this offline and work out a solution with your 2-year old. See if he will be amicable to perhaps sharing the iPad that you purchased with his diaper money.