Why does Ender not tell Shen that he hacked the school’s security system?

Ender believed that because of the ease with which he broke in, the "security system" wasn't really a security system, but rather, another game to win.

If a six-yearold could break them down, they were obviously put there as a plaything, not serious security. Just another game that the teachers set up for us. And this is one I'm good at.