His point was who defines who has the 'need to know' something? It could be argued that the person with the best ability to know whether they might need to know something is receiver, but they cannot judge that need without the information. So the it falls to the holder of the information, and often they might err on the side of caution for confidentiality. The trainer's recommendation was an idea of 'proportionality in context' due to the lack of an authority who can grant us the knowledge of who 'needs to know'.
His issue with 'insight' was 'insight is just when you agree with your therapist; they judge you have gained insight because you say what they have already thought about you'. A brave admission in a room of therapists, but I have enjoyed the challenge as it has allowed me to reflect on how I think about insight and how it happens in the therapy room.
In Psychology insight is said to occur when "the solution to a problem presents itself quickly and without warning." If we take this as a definition then merely agreeing with or confirming a therapist's formulation of the client cannot be insight as it doesn't offer a solution. The faulty idea that the therapist is an expert or authority on what the client needs to be, do, or have also means they cannot be a source of insight as as it will not be happening without warning. I suppose it could be said to be without warning to the client, but the solution is certainly not presenting itself!
As a slightly flimsy analogy I am going to turn to the Hans Christian Andersen story 'The Princess and the Pea'. I am sure you will be familiar with the story but, in a nutshell, a young woman seeking refuge in a castle is proven to be a princess and a worthy bride for the resident prince by feeling a hard pea through 20 mattresses and 20 feather beds with enough discomfort to ruin a night's sleep.
This is where the insight comes in. I as the therapist can intuit that something is happening down in the layers of mattresses, but I cannot know that it is a pea. As we inspect the mattress I might notice the pea and point it out. This allows the Princess to grasp it, know that this is what caused her discomfort, and the solution is to not put it back in the bed. It will also mean that she needs fewer layers of protection and hopefully have both an easier climb into bed ford a better night's sleep in the future.
Insight isn't an appeal to the therapist's 'authority', but rather a disclosure from the client's authority of themselves that allows them to find the solution to a problem.
 Stuart, D. (2017) The thinking revolution: Unleash the full power of your mind, Red Door Publishing