It wasn't that Reidar thought they were the good guys. It was clear they were hiding something and what their intentions were, but since he was going to leave as soon as the sunken turbine quest was complete, he didn't care to find out.
But this… All of this was a colossal mess, and Lena's attack was actively preventing him from leaving.
Reidar swore to buy something that would allow him to collect information so easily that he would not be played like this again. Of course, all of these events were new to him, and that was why he was caught in the mess. This was also a lesson for him to not be greedy.
He constantly dealt with lying and shrewd people because of his work, and that was why he understood Aaron's, Mara's, and Martin's intentions so soon; in fact, less than a week passed since he got to Havenwood.
