Yes, it's true -- people who are thinking of committing suicide are more likely to do so after hearing about someone else who commits suicide. (This is also true for other acts, like murder-suicides.) There's a lot of research on this.
But it doesn't necessarily follow that the right response is to try to cover up suicides. For one thing, people who are at Caltech are bound to hear of anyone who commits suicide at Caltech. For another, it's hard to cover up anything that happens to someone, particularly a young person, in the era of Facebook and Twitter. Third, counseling can actually work for those who get the counseling. Most suicidal people can be helped by one strategy or another: cognitive-behavioral therapy, antidepressant drugs... even just frank discussion can help. Remember, a large number of suicide attempts (in the USA, at any rate, and especially among women) aren't actually meant to succeed. Just because the phrase "a cry for help" is a hopeless cliche doesn't mean that most suicides are not, in fact, cries for help.
And, of course, even if some genius psychometrician crunched numbers on all the above scenarios and concluded that the best response to a suicide would be a coverup and the silent treatment... nobody would believe it, and the school would get hammered, in public and in court, for trying such a policy. After all, the same aspects of culture that recognize many suicide attempts as desperate last-ditch cries for help also recognize that the appropriate response of your friends and family is to... offer help.