The evidence for this is again from the first chapter, where Nguyen, a businessman, does not expect much from Artemis, but is shocked and even frightened by how intelligent he really is. Artemis also does not crack under pressure, which makes him able to distribute fear into a lot of people.
This is why Artemis Fowl can be very deceiving, and throughout the book, a very strange and confusing character to follow. There are three books throughout this whole series, so maybe the theme about Artemis will change, but, for now, this is who Artemis Fowl really is, and cannot deny his own true feelings