Currently all users an see a Security entry in the form to create a new task: "Security settings will override permissions and projects as needed." + dropdown menu. This shouldn't be there.
According to T50: Restricting access to tasks based on project membership, the idea is that users can file a task as Security related by adding the "Security" project-keyword.
If we need to make short term compromises, then one option would be to show that field only to members of the Triagers team. But showing that option to everybody and let them edit it sound like an overkill and a source of confusion and mess. Imagine: what is this field here? let me try... Ooops, where is my task!!!