Good catch and I totally agree, this was utterly stupid. The guy is excited about meeting new species and lacks prudence. It took me a lot of time until I started to like Archer, my first impression was that he was impulsive and stupid.
I think the idea of the show was to show that Archer is just a pilot. He is a regular guy not a captain like the other four, he has not enjoyed a well-rounded Starfleet Academy education, he is out there without any guidelines. The textbooks don't exist yet. He is naive and doesn't want to listen to the advice from the High Command because they are humankind's parents and now the kid entered has entered puberty. This implies a lot of messing up.
After some time he starts to listen to the one Vulcan he trusts though and also takes advice from Phlox, even when it runs against his own instincts.