oomis:”It is showing them he suborns loshon hara, by actively encouraging it”
It isn’t Lashon HaRa when done for a to’eles (and meets the other criteria in Sefer Chofetz Chaim).
“he doesn’t have a more intelligent, productive, and proper way to get the information he needs to make a good decision (i.e. speaking to the child’s FORMER principal and teachers”
Contemporaries provide an important, different perspective then teachers and principals can provide. Additionally, friends may know information the child has taken pains to hide from figures of authority.
“not to mention the most important person – the actual child”
If you have ever interviewed someone for a job or school you would know that everyone puts their best foot forward for the interview, and without doing some prior research the value of the interview is seriously diminished.