Probably caused by someone that was trying to find an SQL injection. It's not really that big of a deal, it's a pretty big edge case to filter out non-relevant searches.
Although this makes practical sense, maybe OP is more motivated to work for companies that make society better versus large corporations that pay a lot.
To me a startup isn't about the money, but introducing my idea to the world. The idea of satisfying a need is enough.
That being said, the money is still a great incentive since you're taking a huge financial and personal risk, but you can still live pretty damn well with $500k/year.
I'm taking Coursera's Introduction to Functional Programming with Scala and Machine Learning classes and Udacity's Intro to Parallel Programming class. All out of interest.
I really recommend Machine Learning, this is my second time taking it (taking as a refresh). It really gives a good introduction on how to predict or classify data.
If you want something more practical, Introduction to Functional Programming with Scala is really informative, teaches you Scala and gives you another perspective on how to make functions and classes. It's definitely a great course for recursion lovers.
He could also be using it the wrong way. Although MongoDB has faults, most of them are well known and developers are warned. MongoDB is far from being perfect, but the most common reason people hate on MongoDB is because they did things the wrong way or for the wrong reasons.