In my opinion, my apologies if it's not correct to speak, it's useless to talk about the past,
And it's useless not to give him an opportunity because "he now acts good but in reality he is stupid, even though he acts good now". Bullshit. You don't have to trust your entire life in this decision. This is a videogame and you don't lose anything by accepting him.
Objectively speaking, if his attitude is correct, prudent and friendly as many members from VU saw, then he (continuing by that path) will succeed and reach the full VU tag in the mean time.
If not, and he is just hiding his real face, then that's why the trainee tag exists. He will surely join, be under widely open eyes from the Circles, observated, judged, and in the minimal action he will be dragged out of the clan. Simple. VU doesn't lose anything.
What will he do then? Attack the forums by ddos? No, man.