My first thought was that it would have made more sense for them to say "now we know that you know all things because you don`t need to ask any questions" (ie you`re omniscient).Now we can see that you know all things and that you do not even need to have anyone ask you questions. This makes us believe that you came from God.”
But that`s not what is written. Instead the interpretation has to be "now we can see you know all things because you can read our thoughts and answer our questions without us even having to ask them, and so don`t need us to express those questions verbally".
Is the latter your interpretation also?